BUR/Safe Digging/TBT-BUR-009

Working Near Sewers and Drains

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Working Near Sewers and Drains

Toolbox Talk Record

Ref: TBT-BUR-009  |  Issue: 1  |  Date: March 2026
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What?

  • Sewers and drains carry foul water, surface water, or combined flows and are found beneath most sites.
  • Striking a live sewer releases raw sewage, creating biological hazards and environmental pollution.
  • Sewer depths vary significantly; some are shallow but combined sewers can be several metres deep.
  • Hydrogen sulphide gas builds up in sewers and can cause unconsciousness and death within seconds.
  • Sewer records may be inaccurate; actual positions can differ from maps by several metres.
  • Opening manholes on live sewers creates confined space risks and exposure to biological hazards.
  • The Water Industry Act 1991 protects public sewers; damaging them can result in prosecution.
  • Working near sewers also creates risk of contamination to the water supply network nearby.
  • New connections to live sewers require approval from the sewerage undertaker before work begins.
  • HSG47 guidance on avoiding danger from underground services applies to sewer location and excavation.

Why?

Biological hazardsRaw sewage contains bacteria, viruses, and parasites that cause serious illness including hepatitis, leptospirosis, and gastroenteritis.
Gas exposureHydrogen sulphide and methane accumulate in sewers. Opening manholes or striking a sewer can release lethal concentrations instantly.
Environmental damageSewer damage causes raw sewage to pollute watercourses and groundwater, leading to Environment Agency prosecution.
Legal liabilityDamaging a public sewer without authority breaches the Water Industry Act 1991 and incurs repair costs and fines.
Do Don't
  • Obtain sewer records and check for both foul and surface water drainage.
  • Use CAT and Genny scanning combined with trial holes to locate sewers.
  • Hand dig within 500mm of a known sewer to avoid mechanical damage.
  • Monitor for hydrogen sulphide gas when opening manholes or working near sewers.
  • Wear appropriate PPE including gloves and face protection near live sewers.
  • Obtain approval from the sewerage undertaker before making new connections.
  • Cover open manholes and excavations to prevent people and debris falling in.
  • Wash hands thoroughly after any contact with sewage or sewer infrastructure.
  • Report any accidental sewer damage immediately to the sewerage undertaker.
  • Vaccinate at-risk workers against hepatitis A and tetanus as recommended.
  • DON'T use mechanical excavation within 500mm of a known sewer position.
  • DON'T open sewer manholes without checking for hazardous gas first.
  • DON'T enter a live sewer or manhole without confined space entry procedures.
  • DON'T assume sewer record drawings are accurate; always verify on site.
  • DON'T discharge construction water or chemicals into the sewer without consent.
  • DON'T touch your face, eat, or drink after contact with sewage-contaminated material.
  • DON'T connect to a public sewer without the sewerage undertaker's written approval.
  • DON'T leave excavations near sewers unsupported; ground movement can fracture pipes.
  • DON'T ignore unusual smells during excavation; they may indicate a damaged sewer.
  • DON'T dispose of contaminated soil or water without proper waste classification.

See also: Safe Digging Practices (HSG47) | CAT and Genny Safe Use
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