Amendment of the 2016 Regulations2

1

The 2016 Regulations are amended as follows

2

In regulation 2 (interpretation)—

a

in paragraph (1)—

i

omit the definitions of “audit monitoring” and “check monitoring”;

ii

insert in the appropriate places—

  • E. coli” means Escherichia coli;

  • “monitoring of a Group A parameter” has the meaning given in regulation 5(1);

  • “monitoring of a Group B parameter” has the meaning given in regulation 5(3);

  • “monitoring programme” means a programme for the identification of, and collection of data on, any substance or organism identified during a risk assessment to confirm compliance with the prescribed concentrations set out in Schedule 1 which—

    1. a

      consists of either or both of the following—

      1. i

        collection and analysis of discrete water samples;

      2. ii

        measurements recorded by a continuous monitoring process, and

    2. b

      may in addition consist of either or both of the following—

      1. i

        inspections of records of the functionality, and maintenance status, of equipment;

      2. ii

        inspections of the catchment area, water abstraction, treatment, storage and distribution infrastructure;

  • “suitably accredited body” means the Secretary of State or a person acting on behalf of the Secretary of State;

b

in paragraph (3)—

i

omit “, other than a structure at a treatment works”;

ii

after “stored for the” insert “sole”.

3

In regulation 4(1) (wholesomeness) after “Water supplied to premises” insert “that is intended for human consumption including”.

4

In regulation 5 (interpretation and application of Part 4)—

a

for paragraphs (1) to (3) substitute—

1

In this Part, “monitoring of a Group A parameter” means monitoring of a Group A parameter for the purpose of obtaining information at regular intervals—

a

as to the organoleptic and microbiological quality of water;

b

where relevant, as to the effectiveness of drinking water treatment, particularly for the purposes of disinfection, for the purposes referred to in paragraph (2); and

c

as regards indicator parameters, whether water supplied for regulation 4(1) purposes meets the specifications for those parameters.

2

A Group A parameter must be monitored to determine whether its presence in water supplied for regulation 4(1) purposes satisfies the provisions of Part 3 or, if a departure has been authorised under Part 7 in relation to that supply, the provisions of Part 3 as read with the terms of that departure.

3

In this Part, “monitoring of a Group B parameter” means monitoring of a Group B parameter for the purpose of obtaining information from which it may be established whether water supplied for regulation 4(1) purposes—

a

satisfies the provisions of Part 3 or, if a departure has been authorised under Part 7 in relation to that supply, the provisions of Part 3 as read with the terms of that departure;

b

meets the specifications for indicator parameters;

c

in respect of other parameters identified as relevant by the Secretary of State under regulation 9, meets the specifications for those parameters.

b

after paragraph (5) insert—

6

In this regulation—

  • “Group A parameter” means a parameter specified in column 2 of Table 1 in Schedule 3;

  • “Group B parameter” means a parameter specified in column 2 of Table 2 or, as the case may be, Table 3 in Schedule 3.

5

In regulation 6 (monitoring: general provisions)—

a

for paragraph (3) substitute—

3

Except in a case to which paragraph (16) applies, the parameters listed in Tables A and B in Schedule 1 and the indicator parameters must be subject to—

a

monitoring of a Group A parameter if the parameter is one listed in column 2 of Table 1 in Schedule 3 and the circumstances specified in column 3 of that Table apply;

b

monitoring of a Group B parameter in any other case.

b

in paragraph (4)—

i

omit “Clostridium perfringens”;

ii

for “3, 10 and 11” substitute “9 and 10”;

c

for paragraph (5) substitute—

5

Compliance samples for chemical parameters including copper, lead and nickel must take the form of a random daytime sample of one litre volume taken at a consumer’s tap without prior flushing.

d

in paragraph (7), for “monitoring”, in the second place it appears, substitute “surveillance”;

e

in paragraph (15) for “2 and 3” substitute “8 to 13 (as applicable)”;

f

in paragraph (16)(a) for “48 hours after” substitute “at”.

6

In regulation 8(1) (authorisation of supply points) for “items 7 to 16 and 19 to 28 in column 1 of Table 3” substitute “item 6 in column 1 of Table 1, and as items 1 to 11 and 14 to 21 in column 1 of Table 3”.

7

For regulation 9 substitute—

Number of samples9

1

In each year a water undertaker must take or cause to be taken from its sampling points or, to the extent authorised under regulation 8, from its supply points, the standard number of samples for analysis of residual disinfectant and each parameter listed in—

a

column 2 of Table 1 in Schedule 3 (Group A parameters);

b

column 2 of Table 2 in Schedule 3 (Group B1 parameters);

c

column 2 of Table 3 in Schedule 3 (Group B2 parameters);

d

column 2 of Table 4 in Schedule 3 (Group A1 parameters);

e

column 2 of Table 5 in Schedule 3 (Group A2 parameters);

f

column 2 of Table 6 in Schedule 3 (Group A3 parameters);

g

column 2 of Table 7 in Schedule 3 (Group A4 parameters).

2

In respect of any parameter not referred to in paragraph (1), the Secretary of State may specify—

a

the number of samples which a water undertaker must take or cause to be taken from its sampling points in each year;

b

its prescribed concentration or value.

3

Samples required to be taken by this regulation must—

a

be taken at regular intervals;

b

in respect of sampling for chemical parameters in the distribution network other than sampling at a consumer’s tap, be taken and handled in accordance with international standard ISO 5667-5 entitled “Water quality. Sampling. Guidance on treatment of drinking water from treatment works and piped distribution systems4; and

c

in respect of microbiological parameters in the distribution network and at a consumer’s tap, be taken and handled in accordance with European standard EN ISO 19458 entitled “Water Quality – Sampling for microbiological analysis”5 using sampling procedure A in the distribution network and sampling procedure B at a consumer’s tap.

4

Subject to paragraph (5), the Secretary of State may, in respect of any supplies of water by a water undertaker to a water supply zone, treatment works, supply points or a service reservoir, give the water undertaker written notice of any variation of—

a

the parameters subject to sampling (by the omission or addition of parameters);

b

the number of samples which the undertaker must take in the period specified in the notice.

5

Paragraph (4) does not apply in relation to E. coli.

6

The Secretary of State may give a notice under paragraph (4)—

a

on the Secretary of State’s own motion; or

b

where paragraph (8) applies, upon application by a water undertaker.

7

A notice under paragraph (4)—

a

must specify which parameters are subject to a variation;

b

must specify the extent of any variation from the standard number of samples required to be taken under paragraph (1) or from the number of samples required to be taken under paragraph (2);

c

may require a risk assessment to be undertaken;

d

may be revoked or varied by the Secretary of State.

8

This paragraph applies where—

a

a risk assessment complying with this regulation has been undertaken and indicates that no factor can be reasonably anticipated to be likely to cause deterioration of the quality of the water;

b

in the case where the water undertaker seeks to cease monitoring a particular parameter, the results from samples taken in respect of the parameter collected at regular intervals over a period of at least three years are all at less than 30% of the parametric value of the parameter; and

c

in the case where the water undertaker seeks to reduce the frequency of monitoring in respect of a particular parameter, the results from samples taken in respect of that parameter collected at regular intervals over a period of at least three years are all at less than 60% of the parametric value of the parameter.

9

The Secretary of State must by further written notice withdraw a notice given under paragraph (4) if the Secretary of State believes that any parameter in the water supply to which the notice relates contravenes the prescribed concentration or value or is likely to do so.

10

A water undertaker given a notice under paragraph (4) must institute a monitoring programme which must be kept under annual review.

11

A risk assessment complies with this regulation where—

a

it meets the principles of European Standard EN 15975-2 entitled “Security of drinking water supply – Guidance for risk and crisis management – Part 2: Risk management”6 or of other equivalent standards accepted at international level;

b

it is subject to a system of quality control which is checked from time to time by a suitably accredited body; and

c

it takes into account the results of monitoring conducted under the second paragraph of Article 7(1) and Article 8 of Directive 2000/60/EC of the European Parliament and of the Council establishing a framework for Community action in the field of water policy7.

12

In this regulation “the standard number” means the number of samples specified in Part 2 or Part 3 of Schedule 3 in respect of a parameter specified in Part 1 of that Schedule.

8

Omit regulation 11.

9

In regulation 13 (sampling at treatment works)—

a

in paragraph (1) for “paragraphs (2), (4) and (6)” substitute “paragraph (6)”;

b

omit paragraphs (2) to (4);

c

in paragraph (6) for “the reduced number” substitute “the number specified in a current notice given by the Secretary of State under regulation 9 which departs from the standard number”;

d

after paragraph (6) insert—

7

In this regulation, “the standard number” has the same meaning as in regulation 9

10

In regulation 14 (sampling at service reservoirs) after “in use” insert “or as specified in a notice given by the Secretary of State under regulation 9(3)”.

11

For regulation 16 substitute—

Collection and analysis of samples16

1

Every water undertaker or wholesale licensee must secure, so far as reasonably practicable, that when it takes, handles, transports, stores or analyses any sample required to be taken for the purposes of Part 4 or this Part, or causes any such sample to be taken, handled, transported, stored or analysed, it complies with the appropriate requirements.

2

Every water undertaker or wholesale licensee must secure that a suitably accredited body checks from time to time its compliance with the appropriate requirements.

3

Additionally, any person involved in seeking to discharge the obligation described in paragraph (1) must ensure that—

a

the methods of analysis used by that person for the purposes of monitoring and demonstrating compliance with this Part are validated and documented in accordance with European standard EN ISO/IEC 17025 entitled “General requirements for the competence of testing and calibration laboratories8 or other equivalent standards accepted at international level; and

b

that person applies quality management system practices in accordance with European standard EN ISO/IEC 17025 or other equivalent standards accepted at international level.

4

Every water undertaker or wholesale licensee must maintain such records as are sufficient to enable it to establish, in relation to each sample taken for the purposes of Part 4 or this Part, that such of the appropriate requirements as are applicable to that sample have been satisfied.

5

Subject to paragraph (6), for the purpose of establishing, within acceptable limits of deviation and detection, whether the sample contains concentrations or values which contravene the prescribed concentrations or values, or exceed the specifications for indicator parameters—

a

the method of analysis specified in column 2 of Table A1 in Schedule 5 must be used for the parameter specified in relation to that method in column 1;

b

the method of analysis in respect of the parameters listed in column 1 of Table A3 in Schedule 5 must be capable of measuring concentrations equal to the parametric value with a limit of quantification of 30% or less and an uncertainty of measurement as specified in column 2 of that Table and the result must be expressed—

i

using at least the same number of significant figures as the parametric value, and

ii

in the same units laid down in these Regulations; and

c

the method of analysis used for the odour and taste parameters (items 5 and 7 in Part 2 of Table B in Schedule 1) must be capable, at the time of use, of measuring values equal to the parametric value with a precision or uncertainty of measurement of 1 dilution number at 25°C.

6

The Secretary of State may, on the application of any person, authorise a method of analysis other than that specified in paragraph (5)(a) (“the prescribed method”).

7

An application for the purposes of paragraph (6) must be made in writing and must be accompanied by—

a

a description of the method of analysis; and

b

the results of the tests carried out to demonstrate the reliability of that method and its equivalence to the prescribed method.

8

But the Secretary of State must not authorise the use of the method proposed in the application unless the Secretary of State is satisfied that the results obtained by the use of that method are at least as reliable as those produced by the use of the prescribed method.

9

An authorisation under paragraph (6) may be subject to such conditions as the Secretary of State considers appropriate.

10

The Secretary of State may at any time, by notice in writing served on the water undertaker or wholesale licensee to which an authorisation under paragraph (6) has been given, revoke the authorisation, but any such notice must be served no later than 3 months before the date on which the revocation is stated to take effect.

11

In this regulation, “appropriate requirements” means such of the following requirements as are applicable—

a

the sample is representative of the quality of the water at the time of sampling;

b

the person taking the sample is doing so in accordance with a system of quality control to an appropriate standard;

c

the sample is not contaminated in the course of being taken;

d

the sample is kept at such a temperature and in such conditions as will secure that there is no material alteration of the concentration or value for the measurement or observation of which the sample is intended;

e

the sample is analysed, whether at the time and place it is taken or as soon as reasonably practicable after it is taken—

i

by or under the supervision of a person who is competent to perform that task; and

ii

with the use of such equipment as is suitable for the purpose

12

In regulation 34 (maintenance of records) in paragraphs (1)(h) and (2)(ca)9 omit “made”.

13

For Schedule 3, substitute—

SCHEDULE 3Monitoring

Regulation 6

PART 1Group A and Group B parameters

Table 1Group A parameters and circumstances for monitoring

(1) Item number

(2) Parameter

(3) Circumstances

1

Aluminium

Where used as a water treatment chemical or where the water originates from, or is influenced by, surface waters

2

Ammonium

Where chloramination is practised

3

Coliform bacteria

In all circumstances

4

Colony counts 22°C

In all circumstances

5

Colour

In all circumstances

6

Conductivity(1)

In all circumstances

7

E. coli

In all circumstances

8

Hydrogen ion

In all circumstances

9

Iron

Where used as a water treatment chemical or where the water originates from, or is influenced by, surface waters

10

Manganese

Where the water originates from, or is influenced by, surface waters

11

Nitrate

Where chloramination is practised

12

Nitrite

Where chloramination is practised

13

Odour

In all circumstances

14

Residual disinfectant

In all circumstances

15

Taste

In all circumstances

16

Turbidity

In all circumstances

(1)

Sampling for this parameter in water supply zones may be substituted by sampling at supply points.

Table 2Group B1 parameters and circumstances for monitoring to be used for sampling in water supply zones (or supply points)

(1) Item number

(2) Parameter

(3) Circumstances

1

Aluminium

Where not used as a water treatment chemical or where the water neither originates from, nor is influenced by, surface waters

2

Ammonium

Where chloramination is not practised

3

Antimony

In all circumstances

4

Arsenic

In all circumstances

5

Benzene(1)

In all circumstances

6

Benzo(a)pyrene

In all circumstances

7

Boron (1)

In all circumstances

8

Bromate (2)

In all circumstances

9

Cadmium

In all circumstances

10

Chloride (1)

In all circumstances

11

Chromium

In all circumstances

12

Clostridium perfringens (including spores)

In all circumstances

13

Copper

In all circumstances

14

Cyanide(1)

In all circumstances

15

1, 2 dichloroethane (1)

In all circumstances

16

Enterococci

In all circumstances

17

Fluoride (1)

In all circumstances

18

Gross alpha (1)(3)(4)

In all circumstances

19

Gross beta (1)(3)(4)

In all circumstances

20

Iron

Where not used as a water treatment chemical or where the water neither originates from, nor is influenced by, surface waters

21

Lead

In all circumstances

22

Manganese

Where the water neither originates from, nor is influenced by, surface waters.

23

Mercury (1)

In all circumstances

24

Nickel

In all circumstances

25

Nitrate

Where chloramination is not practised

26

Nitrite

Where chloramination is not practised

27

Pesticides and related products (1)

In all circumstances

28

Polycyclic aromatic hydrocarbon

In all circumstances

29

Radon (1)(4)

In all circumstances

30

Selenium

In all circumstances

31

Sodium

In all circumstances

32

Sulphate (1)

In all circumstances

33

Tetrachloroethene (1)

In all circumstances

34

Tetrachloromethane (1)

In all circumstances

35

Total organic carbon (1)

In all circumstances

36

Trichloroethene

In all circumstances

37

Trihalomethanes: Total

In all circumstances

38

Tritium (1)(4)

In all circumstances

(1)

Sampling for these parameters may be within water supply zones (Group B1) or at supply points (Group B2).

(2)

Monitoring of this parameter in water supply zones is required only where sodium hypochlorite is added after water has left the treatment works. In other circumstances, monitoring is required at supply points (see Group B2).

(3)

To monitor for indicative dose.

(4)

In the event that a single sample is taken in a year, a further sample must be taken if there is any change in relation to that supply that could affect the concentration of radionuclides in the water supply.

Table 3Group B2 parameters and circumstances for monitoring to be used for sampling at works or supply points

(1) Item number

(2) Parameter

(3) Circumstances

1

Benzene (1)

In all circumstances

2

Boron (1)

In all circumstances

3

Bromate (2)

In all circumstances

4

Chloride (1)

In all circumstances

5

Clostridium perfringens (including spores)

In all circumstances

6

Cyanide (1)

In all circumstances

7

1, 2 dichloroethane (1)

In all circumstances

8

Fluoride (1)

In all circumstances

9

Gross alpha (1)(3)(4)

In all circumstances

10

Gross beta (1)(3)(4)

In all circumstances

11

Indicative dose

In all circumstances

12

Mercury (1)

In all circumstances

13

Nitrite

When chloramination is not practised

14

Pesticides and related products (1)

In all circumstances

15

Radon (1)(4)

In all circumstances

16

Sulphate (1)

In all circumstances

17

Tetrachloroethene (1)

In all circumstances

18

Tetrachloromethane (1)

In all circumstances

19

Total organic carbon (1)

In all circumstances

20

Trichloroethene

In all circumstances

21

Tritium (1)(4)

In all circumstances

(1)

Sampling for these parameters may be within water supply zones (Group B1) or at supply points (Group B2).

(2)

Monitoring is required at supply points where sodium hypochlorite is not added after water has left the treatment works. In other circumstances, see Group B1.

(3)

To monitor for indicative dose.

(4)

In the event that a single sample is taken in a year, a further sample must be taken if there is any change in relation to that supply that could affect the concentration of radionuclides in the water supply.

Table 4Group A1 parameters

(1) Item number

(2) Parameter

1

Coliform bacteria

2

E. coli

3

Residual disinfectant

Table 5Group A2 parameters

(1) Item number

(2) Parameter

1

Coliform bacteria

2

Colony counts 22°C

3

E. coli

4

Nitrite

5

Residual disinfectant

6

Turbidity

Table 6Group A3 parameters

(1) Item number

(2) Parameter

1

Conductivity

Table 7Group A4 parameters

(1) Item number

(2) Parameter

1

Aluminium

2

Ammonium

3

Colony counts 22°C

4

Colour

5

Conductivity

6

Hydrogen ion

7

Iron

8

Manganese

9

Nitrate

10

Nitrite

11

Odour

12

Taste

13

Turbidity

PART 2Annual sampling frequencies: water supply zones

Annual sampling frequencies for Group A4 parameters: water supply zones

This table and each table which follows it in this Part set out the annual sampling frequencies for all the substances and parameters comprising each of the groups to which they correspond, those groups having been outlined in Part 1 of this Schedule. These are determined for each water supply zone according to its estimated population (as specified in column 1 of each table in this Part). The number of samples to be taken is the standard number specified in column 2, unless a notice varying this number has been given under regulation 9.

For the purposes of this table, where the population is not an exact multiple of 5,000, the population figure must be rounded up to the nearest multiple of 5,000.

Table 8Annual sampling frequencies for Group A4 parameters: water supply zones

(1) Estimated population of water supply zone

(2) Standard sampling frequency per year

<100

2

100-4,999

4

5,000-9,999

12

10,000-29,999

24

30,000-49,999

36

50,000-79,999

52

80,000-100,000

76

Table 9Annual sampling frequencies for Group B1 parameters: water supply zones

(1) Estimated population of water supply zone

(2) Standard sampling frequency per year

<100

1

100-4,999

4

5000-100,000

8

Table 10Annual sampling frequencies for Group A1: water supply zones

(1) Estimated population of water supply zone

(2) Standard sampling frequency per year

<100

4

≥100

12 per 5,000 population

For the purposes of this table, where the population is not an exact multiple of 5,000, the population figure must be rounded up to the nearest multiple of 5,000.

PART 3Annual sampling frequencies: treatment works and supply points

Annual sampling frequencies for Group A2 parameters: treatment works or supply points

This table and each table which follows it in this Part set out the annual sampling frequencies for all the substances and parameters comprising each of the groups to which they correspond at treatment works or supply points, those groups having been outlined in Part 1 of this Schedule. The frequencies are determined according to the volume of water supplied at each treatment works or supply point. The number of samples to be taken is the standard number specified in column 2, unless a notice varying this number has been given under regulation 9.

Table 11

(1) Volume of water supplied m3/day

(2) Standard sampling frequency per year

<20

4

20-1,999

12

2,000-5,999

104

6,000-11,999

208

≥12,000

365

Table 12Annual sampling frequencies for Group A3 parameters: supply points

(1) Volume of water supplied m3/day

(2) Standard sampling frequency per year

<20

2

20-999

4

1,000-1999

12

2,000-5,999

24

6,000-9,999

36

10,000-15,999

52

16,000-32,999

104

33,000-49,999

156

50,000-67,999

208

68,000-84,999

260

85,000-101,999

312

102,000-119,999

365

120,000-241,999

730

242,000-484,999

1,460

485,000-728,999

2,190

Table 13Annual sampling frequencies for Group B2 parameters: treatment works or supply points

(1) Volume of water supplied m3/day

(2) Standard sampling frequency per year

<20

1

20-999

4

1,000-49,999

8

50,000-89,999

12

90,000-299,999

24

300,000-649,999

36

≥650,000

48

14

In Schedule 4 (monitoring for indicative dose and analytical performance characteristics)—

a

in paragraph 4(1) (calculation of the ID), for paragraph (a) substitute—

a

the measured radionuclide concentrations and the dose coefficients referred to as “standard values and relationships” in Article 13, and recommended for the estimation of doses from internal exposure in the definition of “standard values and relationships” in Article 4(96), of Council Directive 2013/59/Euratom laying down basic safety standards for protection against the dangers arising from exposure to ionising radiation10, or

b

in the text immediately following the title to Table 1, for the words from “laid down” to “96/29/Euratom” substitute “referred to as “standard values and relationships” in Article 13, and recommended for the estimation of doses from internal exposure in the definition of “standard values and relationships” in Article 4(96), of Council Directive 2013/59/Euratom”.

15

In Schedule 5 (analytical methodology)—

a

for Table A1, substitute—

Table A1Microbiological parameters for which, subject to regulation 16(6), methods of analysis are specified

(1) Parameter

(2) Method of analysis

E. coli and coliform bacteria

EN ISO 9308-111 or EN ISO 9308-212

Enterococci

EN ISO 7899-213

Pseudomonas aeruginosa

EN ISO 1626614

Enumeration of culturable microorganisms – colony count 22°c

EN ISO 622215

Enumeration of culturable microorganisms – colony count 36°c

EN ISO 6222

Clostridium perfringens (including spores)

EN ISO 1418916

b

omit Table A2;

c

at the end insert—

Table A3Minimum performance characteristic uncertainty of measurement

The uncertainty of measurement laid down in this table must not be used as an additional tolerance to the parmetric value set out in Schedules 1 and 2.

(1) Parameters

(2) Uncertainty of measurement % of the parametric value (except for pH) (1)

Aluminium

25

Ammonium

40

Antimony

40

Arsenic

30

Benzene

40

Benzo(a)pyrene (2)

50

Boron

25

Bromate

40

Cadmium

25

Chloride

15

Chromium

30

Colour

20

Conductivity

20

Copper

25

Cyanide (3)

30

1,2-dichloroethane

40

Fluoride

20

Hydrogen ion concentration pH (expressed in pH units)

0.2

Iron

30

Lead

25

Manganese

30

Mercury

30

Nickel

25

Nitrate

15

Nitrite

20

Oxidisability (4)

50

Pesticides (5)

30

Polycyclic aromatic hydrocarbons (6)

50

Selenium

40

Sodium

15

Sulphate

15

Tetrachloroethene (7)

30

Tetrachloromethane

30

Trichloroethene (7)

40

Trihalomethanes: total (6)

40

Total organic carbon (8)

30

Turbidity (9)

30

(1)

“Uncertainty of measurement” is a non-negative parameter characterising the dispersion of the quantity values being attributed to a measurement, based on the information used. The performance criterion for measurement uncertainty (k = 2) is at least the percentage of the parametric value stated in the table.

(2)

If the value of uncertainty of measurement cannot be met, the best available technique must be selected (up to 60% of the parametric value).

(3)

The method determines total cyanide in all forms.

(4)

Reference method: European standard EN ISO 8467 entitled “Water quality – Determination of permanganate index (ISO 8467)”17.

(5)

The performance characteristics for individual pesticides are given as an indication. Values for the uncertainty of measurement as low as 30% can be achieved for several pesticides, higher values up to 80 % may be allowed for a number of pesticides.

(6)

The performance characteristics apply to individual substances, specified at 25% of the parametric value in Part I of Table B in Schedule 1.

(7)

The performance characteristics apply to individual substances, specified at 50% of the parametric value in Part I of Table B in Schedule 1.

(8)

The uncertainty of measurement must be estimated at the level of 3 mg/l of the total organic carbon (TOC) in accordance with European standard EN 1484 entitled “Water analysis – Guidelines for the determination of total organic carbon and dissolved organic carbon”18.

(9)

The uncertainty of measurement must be estimated at the level of 1.0 nephelometric turbidity units) in accordance with European standard EN ISO 7027-1 entitled “Water quality – Determination of turbidity – Part 1: Quantitative methods (ISO 7027-1”19.