Details

Boiler blowdown - is the excess liquid from water based heating systems , which are routinely flushed to maintain/improve system efficiencies and maintenance. Certain heating systems use water filled pipes which are dosed with corrosion inhibitors. These may discharge liquid or blowdown on a regular basis. Depending on the nature and concentration of the chemicals, blowdown may be classifiable as hazardous waste or may be suitable for discharge to foul sewer under consent.

The following regulations must be consulted in order to safely and legally dispose of this effluent:

Water Resources Act 1991

The Water Resources Act is designed to protect "controlled waters" which includes rivers, streams, ditches, ponds, territorial waters (within 3 miles of national boundary) and groundwater. Surface water drains are used to discharge rainwater from sites into controlled waters (including to groundwater via soakaway).

Consequently, such drains are an important pathway for carrying spillages into controlled waters. These discharges receive no form of treatment (as they would from a sewage treatment works via foul sewer) and as a result many major pollution incidents occur from pollutants travelling down surface water drains each year. Such pollution will normally constitute a breach of Section 85 of the Act, under which it is an offence to "cause or knowingly permit any poisonous, noxious or polluting matter, or any solid waste to enter controlled waters".

In effect, this legislation makes it an offence to discharge anything other than rainwater into surface water drains and controlled waters without a consent from the regulator.

Water Industry Act 1991

Boiler blowdown is classified as a "trade effluent" - "any liquid, either with or without suspended particles, which is wholly or partly produced in the course of any trade or industry carried on at trade premises". Under the Water Industry Act, companies wishing to discharge trade effluent to foul sewer must hold a consent from the local sewerage undertaker. Charges may be levied according to effluent nature, concentration and volume.

For more information see

Netregs - Trade Effluent