Toolbox talk water pollution

07 Jun 2020 - Flaaim

It is vital to manage water properly on site to protect our environment. If watercourses are polluted, or unacceptable wastes are disposed of to a sewer system, you or the company may end up in court. Industries using water from a river downstream of site may be affected by reduced water quality and sue if this causes damage. The site does not need to be next to a river to cause a problem. Any pollutants getting into a surface water drain or groundwater can end up in a river even if it is miles away. These pollutants can be traced back to source. Spillages can be easily noticed. A gallon of oil can completely cover a lake the size of two football pitches.


There are generally two main types of drainage on site:

Surface water drains are designed to carry uncontaminated rainwater directly to a stream, river or soakaway. These should be colour coded blue. NOTHING should be allowed to enter surface water drains, except rainwater. Materials and plant should not be stored near drains. Even if described as bio-degradable, detergents are not suitable for discharge to surface water drains. Use of detergents should be carried out in designated areas draining to foul sewers.

Foul water drains are designed to carry foul water directly to a sewage works for treatment before being discharged into a watercourse. These should be colour coded red. It is ILLEGAL to discharge into foul sewers without agreement from the sewage undertaker.

It is an offence to cause or knowingly permit any poisonous, noxious or polluting matter or any solid waste matter (which includes cement, silt, concrete, oil, petroleum spirit, sewage or other polluting matter) to enter any controlled waters unless a consent to discharge is authorised by the relevant agency. Road drains and surface water gullies generally discharge into controlled waters and should be treated as such. DO NOT wash tools out in watercourses.

It is vital that a Spillage Response Procedure is in place on all sites. (See Environmental Toolbox Talk EO2.


The risk of fuel spillage is greatest during refuelling. Therefore no refuelling should take place in, over, or adjacent to watercourses. Refuel all plant in a designated area at least 10 meters away from any watercourse.


The most common form of water pollution from construction is suspended sediments-more commonly known as silt. Silt also carries other contaminants e.g. oil, and chemicals. Silt can be removed by:

  1. Settling out in a settlement tank.
  2. Allowing it to infiltrate through a large grassy area (check with the landowner/Environment agency).
  3. Chemical treatment with flocculants/sedimentation.
  4. Pumping to a foul sewer (permission of the sewage undertaker is required)
  5. Pump into a tanker and dispose off site.

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