PREVENTION AND CONTROL OF WATER POLLUTIONCentral

Section 21 of The Water (Prevention and Control of Pollution) Act, 1974

(1)A State Board or any officer empowered by it in this behalf shall have power to take for the purpose of analysis samples of water from any stream or well or samples of any sewage or trade effluent which is passing from any plant or vessel or from or over any place into any such stream or well.
(2)The result of any analysis of a sample of any sewage or trade effluent taken under sub-section (1) shall not be admissible in evidence in any legal proceeding unless the provisions of sub-sections (3), (4) and (5) are complied with.
(3)Subject to the provisions of sub-sections (4) and (5), when a sample (composite or otherwise as may be warranted by the process used) of any sewage or trade effluent is taken for analysis under sub-section (1), the person taking the sample shall--
1. (a)serve on the person in charge of, or having control over, the plant or vessel or in occupation of the place (which person is hereinafter referred to as the occupier) or any agent of such occupier, a notice, then and there in such form as may be prescribed of his intention to have it so analysed;
2. (b)in the presence of the occupier or his agent, divide the sample into two parts;
3. (c)cause each part to be placed in a container which shall be marked and sealed and shall also be signed both by the person taking the sample and the occupier or his agent;
4. (d)send one container forthwith,--
  1. (i)in a case where such sample is taken from any area situated in a Union territory, to the laboratory established or recognised by the Central Board under section 16; and
  2. (ii)in any other case, to the laboratory established or recognised by the State Board under section 17;
5. (e)on the request of the occupier or his agent, send the second container,--
  1. (i)in a case where such sample is taken from any area situated in a Union territory, to the laboratory established or specified under sub-section (1) of section 51; and
  2. (ii)in any other case, to the laboratory established or specified under sub-section (1) of section 52. 1 [(4) When a sample of any sewage or trade affluent is taken for analysis under sub-section (1) and the person taking the sample serves on the occupier or his agent, a notice under clause (a) of sub-section (3) and the occupier or his agent wilfully absents himself, then,--
6. (a)the sample so taken shall be placed in a container which shall be marked and sealed and shall also be signed by the person taking the sample and the same shall be sent forthwith by such person for analysis to the laboratory referred to in sub-clause (i) or sub-clause (ii), as the case may be, of clause (e) of sub-section (3) and such person shall inform the Government analyst appointed under sub-section (1) or sub-section (2), as the case may be, of section 53, in writing about the wilful absence of the occupier or his agent; and
7. (b)the cost incurred in getting such sample analysed shall be payable by the occupier or his agent and in case of default of such payment, the same shall be recoverable from the occupier or his agent, as the case may be, as an arrear of land revenue or of public demand: Provided that no such recovery shall be made unless the occupier or, as the case may be, his agent has been given a reasonable opportunity of being heard in the matter.
(5)When a sample of any sewage or trade effluent is taken for analysis under sub-section (1) and the person taking the sample serves on the occupier or his agent a notice under clause (a) of sub-section (3) and the occupier or his agent who is present at the time of taking the sample does not make a request for dividing the sample into two parts as provided in clause (b) of sub-section (3), then, the sample so taken shall be placed in a container which shall be marked and sealed and shall also be signed by the person taking the sample and the same shall be sent forthwith by such person for analysis to the laboratory referred to in sub-clause (i) or sub-clause (ii), as the case may be, of clause (d) of sub-section (3).

Summary

The State Board or its officers have the right to take water or waste samples from any plant or location to check for pollution.
For a sample result to be used as evidence in court, the officer must follow a very specific legal process.
The officer must immediately notify the person in charge that they plan to have the sample analyzed.
Usually, the sample is split into two parts, sealed in containers, and signed by both the officer and the person in charge.
One part is sent to the Board's own lab, while the other can go to a separate government lab if the owner asks for it.
If the person in charge is purposefully absent, the officer can still take the sample and send it for testing at the owner's expense.

Practical examples

1In October 2025, an inspector takes a sample from a tannery drain, splits it in two, and has the manager sign the seals on both bottles.

2When a factory owner hides in the office during an inspection in 2026, the officer takes a waste sample anyway and records the owner's absence for the laboratory.

FAQ

1. Can a sample result be used in court if the owner was not notified?

No, Section 21 of the 1974 Water Act states that analysis results are not admissible in evidence unless the notice and procedural steps are strictly followed.

2. What happens if the owner does not want the sample split in two?

Under Section 21 of the Water (Prevention and Control of Pollution) Act, 1974, if the owner is present but does not ask for a split, the single sample is sent to the Board's lab.

3. Where is the first part of a water sample sent for testing?

According to Section 21 of the Water Act, the first container is sent to the laboratory established by the Central Board under Section 16 or the State Board under Section 17.

4. Who pays for sample analysis if the owner is absent?

Under Section 21 of the Water Act of 1974, if the owner is willfully absent, the cost of analysis is recovered from the owner as an arrear of land revenue.

Test yourself

Q1.Under Section 21 of The Water (Prevention and Control of Pollution) Act, 1974, what must an officer do immediately when taking a sample?

Q2.If an occupier requests it under Section 21 of the 1974 Water Act, where is the second part of the sample sent for analysis?

Q3.What makes a sample analysis result "not admissible in evidence" under Section 21 of The Water (Prevention and Control of Pollution) Act, 1974?

Q4.Under Section 21 of the Water Act of 1974, what happens if an occupier is "wilfully absent" during sampling?

Q5.How does Section 16 relate to the sampling procedure for Union territories under Section 21 of The Water (Prevention and Control of Pollution) Act, 1974?

Q6.Under Section 21 of the 1974 Water Act, what happens if the owner is present but does not ask for the sample to be divided?

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