Why are Site Drains Painted?

Many sites paint their drains, usually red or blue, but why do they do that and what does it mean?  Why is drain painting considered good practice?  Read this blog to find out.

What do the colours mean?

The colour of painted drains typically indicates the type of drain and where any discharge that enters it will go to.  Blue drains typically indicate surface water drains where the water will be discharged into the environment, usually to a watercourse or a soakaway.  Red drains indicate water discharged to foul drains, which usually lead to water treatment facilities managed by water companies.  You may also have drains with other colours, like yellow or green.  Although it can vary, yellow often indicates an interceptor and could be accompanied by blue or red paint to indicate whether the interceptor is on the surface or the foul line.  Often, green drains are connected to an on-site effluent treatment facility.

Why is drain painting considered best practice?

Under their pollution prevention guidance, the Environment Agency recommends that manhole covers are painted blue for surface water and red for foul water.  But why is this?  Drain painting makes it very easy to identify which drains go where, particularly when combined with directional arrows for effluent flow.  This is particularly useful when needing to select drains, for example, if you are discharging effluent from floor washing, it will need to go down a foul drain (as long as you have a trade effluent consent).  You may also want to think about whether you want to store oils or waste next to blue drains.

Painted drains are of particular interest in the event of an emergency.  If you have a spillage, or contaminated water enters your drains, you must respond quickly to minimise or prevent pollution from leaving your site.  Painted drains will allow you to understand where the pollution will be heading and directional arrows will show you how it will get there, allowing you to make the most informed spill response decisions.  If pollution has left your site, you will need to inform the relevant authority – the Environment Agency for surface water drains (painted blue) and the water company for foul drains (painted red).

How do I know what colours to paint my drains?

You should have an accurate drainage plan for your site (read our previous blog here for what your drainage plan should contain) that indicates where your drains are and whether they are surface or foul water.  You should be confident that your drainage plan is accurate and the arrangements verified prior to painting your drains – you don’t want to get it wrong!

It is generally accepted that painting your drains is best practice, typically blue for surface water and red for foul water.  This will allow you to identify the correct drainage type for operational considerations and also inform your spill response.  It is essential that your drainage is accurately painted and consistent with your drainage plan.