Concrete Washout Procedures

Concrete washout is the water used to clean concrete mixers, pumps, chutes, and tools after placing operations.
Washout water is highly alkaline with a pH above 12, containing cement particles, sand, and chemical admixtures.
Discharging washout water into drains, watercourses, or onto unprotected ground is a criminal offence under pollution regulations.
A designated washout area with an impermeable lined containment system must be established before any concrete work begins.
The washout area must be clearly signed and located away from site drainage, watercourses, and ecologically sensitive areas.
Concrete mixer trucks must discharge their washout water only into the designated containment facility, not onto bare ground.
Solidified washout residue must be removed and disposed of as construction waste through the correct waste stream.
Pump pipeline cleanout water must also be directed to the containment system — it contains the same pollutants as mixer washout.
The Environment Agency can issue unlimited fines and stop-work notices for concrete washout entering any watercourse.
Every person involved in concrete operations must know the washout location and procedure before the pour begins.

Water pollution	Concrete washout kills aquatic life rapidly — its extreme alkalinity and suspended solids destroy river ecosystems for miles downstream.
Unlimited fines	Polluting a watercourse with concrete washout is a criminal offence carrying unlimited fines and potential imprisonment.
Simple prevention	A lined containment area and clear signing prevent all concrete washout pollution — the solution is cheap and straightforward.

Do

Don't

Establish a designated, impermeable-lined washout area before any concrete work begins.
Sign the washout area clearly and brief all concrete workers on its location.
Direct all concrete mixer truck washout to the designated containment facility only.
Contain pump pipeline cleanout water in the same system as mixer washout.
Locate the washout area away from site drains, watercourses, and sensitive habitats.
Remove solidified washout residue regularly and dispose of it as construction waste.
Inspect the washout containment for leaks and capacity before each pour day.
Brief delivery drivers on the washout procedure and location at the site entrance.
Monitor nearby drains for any signs of concrete contamination during pour operations.
Report any washout spill or containment failure to the environmental manager immediately.

DON'T discharge concrete washout water into drains, ditches, or watercourses.
DON'T wash out concrete equipment onto bare ground without impermeable containment.
DON'T begin concrete operations without a designated washout area established on site.
DON'T allow delivery drivers to wash out in undesignated areas of the site.
DON'T locate washout areas near site drainage or ecologically sensitive features.
DON'T let solidified washout residue overflow the containment — clear it regularly.
DON'T use a washout facility that is leaking or near capacity without repair.
DON'T assume drivers know the procedure — brief them at the entrance every time.
DON'T ignore milky or discoloured water in nearby drains — investigate the source.
DON'T delay reporting a washout spill — early containment limits environmental damage.

See also: Fuel and Oil Spill Prevention | Pollution Incident Reporting

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