Drain Interceptors

Drain interceptors, or drain separators, are a defence to stop contaminants from entering surface water drains. At Metro Rod, we're experts in interceptor maintenance, from installations to emptying. Contact us today for a free no-obligation quote.


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Experts in Drain Interceptor Installation and Maintenance

Our engineers are specially trained to install and maintain drain interceptors, ensuring your site is equipped with the correct interceptor and an informed maintenance plan to keep your site running smoothly, minimising the risk of flooding and helping with environmental compliance.


What is a Drain Interceptor?

Drain interceptors or drain separators are a defence to stop contaminants from entering surface water drains. Also referred to as petrol interceptors or oil separators, they are tanks installed within drainage pipework designed to collect and keep hold of contaminants. For example, petrol and oil that wash into the surface water drain during rainfall. The interceptor ensures contaminants do not flow into the main surface water sewers.

Typically, a drain interceptor is found in commercial or industrial sites like petrol stations, car parks, production/manufacturing areas and storage facilities.

How Do Drain Interceptors Work?

Petrol interceptors are used to remove contaminants from surface water before it reaches the main sewer system. This is done through a series of tanks or chambers, the surface water from roads and car parks flows into the first chamber which is vented to remove odours and gases safely. The interceptor is designed to allow heavy solid contaminants to fall and settle at the bottom of the tank, while lighter oils rise to the top.

The remaining water travels through the system and is discharged to the main sewer system as shown in the image below.

Drain Interceptor Image

To find out what type of interceptor is right for your site or to discuss the management of your wastewater, contact your local Metro Rod drainage specialists.


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How Often Should a Drain Interceptor Be Emptied?

Maintenance is key to a functional drain interceptor system to ensure your business not only meets environmental regulations but prevents unexpected flooding and emergency call-outs due to debris causing the drains to block.

The Environment Agency recommends interceptors should be emptied every six months, though this isn’t compulsory guidance. You may be safe to empty interceptors at a lesser frequency. Still, it is the responsibility of your business to prevent pollution on-site, so routine sampling and keeping track of your maintenance is a must.

Give the Drain Interceptor Experts a Call

Drain interceptor installations and maintenance can help your business comply with environmental regulations as well as prevent unnecessary downtime and unexpected call-outs.

For more information or advice, contact your local Metro Rod or call us on 0800 66 88 00. We’re always happy to arrange a free site visit and a no-obligation quote.

Drain Interceptors FAQ

Why are Drain Interceptors needed?

Drain interceptors are essential for controlling contaminants in surface water. They are designed to collect and hold on to oil, petrol and other pollutants to allow the water to pass through the system and into the main sewer line.

What are other names for Drain Interceptors?

Drainage interceptors can also be called interceptor traps, interceptor tanks, oil separators, petrol interceptors and filter tanks. These systems all essentially carry out the same task, separating contaminants from wastewater but are sometimes called different names.

Do Drain Interceptors stop rats?

Preventative measures, including valves, barriers and traps, can help your drain interceptor stay protected from rat entry. Rats are great climbers and swimmers, making it through small pipes, tight bends, and areas with lots of water flow. So while it may take longer, it may not necessarily be stopped by an interceptor system on its own without other preventative measures.

What are Drain Interceptor Alarm and Monitoring systems?

Drain interceptors can be fitted with alarm and monitoring systems that remotely assess how full the system is and give feedback to you on whether it is working effectively. These alarms or monitoring systems can tell you specifically if too high a proportion of a contaminant is reaching the second or third tank within the system or if a tank contains a specified amount of pollutant.

What types of Drain Interceptors are there?

There are several types of interceptors; the two main types are full retention interceptors and bypass interceptors.

Full retention interceptors are designed to be used in high-risk areas. They treat the full flow of water passing through the interceptor. These are usually in place in high-risk sites such as petrol forecourts, fuel depots, manufacturing plants and high-flow traffic areas.

Bypass interceptors are used where there is an acceptable risk of not providing full flow treatment, such as car parks and roadways. During periods of heavy rainfall, the interceptor treats the initial volume and then allows a percentage of the rain to bypass the treatment section of the interceptor.