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Based in the West Midlands, we carry out the maintenance, service and repair of Graf sewage treatment plants. These include One2Clean, OneAdvanced and Klaro E Professional models. With over 25 years experience in sewage solutions, including treatment plants, cesspools and septic tanks, we've built up specialist expertise and take real pride in delivering excellent customer service.

Graf sewage treatment plant service

We offer full servicing of Graf sewage treatment plants, for domestic and commercial properties. Our team of engineers have over 25 years of experience in the industry, and are highly knowledgeable at sewage treatment plant diagnostics. Our team can identify any faults within the tank, and assess if the Graf sewage treatment plant is compliant or not. 


As Graf accredited installers of sewage treatment plants, we recognise it's a big investment and it's not something you want to replace in a hurry! When maintained properly, a Graf sewage treatment system can last over 20 years.


Our engineers can identify any warning signs and look to address them, to maximise your tank’s potential and ensure it is functioning properly now, and in the future.

Sewage treatment plant repairs

As Graf accredited installers of Graf sewage treatment plants, we are able to carry out repairs to extend your tank’s lifespan and ensure it is functioning properly and safely.


We stock a wide range of parts, so that we can offer quick and hassle-free repairs of your Graf sewage treatment plant. Our knowledgeable engineers have over 25 years experience in the industry, so you can be rest assured your Graf sewage treatment plant is in safe hands. 


There may be a fault with your system if the control panel shows a red light and makes a noise. This is a good indication that you need a service engineer to assess the possible malfunction within the tank. 


​Contact us today for expert advice!​

Benefits of our service package

Peace of Mind

Get peace of mind that your system is maintained correctly and minimise the risk of unexpected breakdowns and nasty odours when you least want it!

Service report provided

We provide you with a service report after each visit to let you know how the plant is functioning and include detailed photos.

Prolong your system

A sewage system is a big cost outlay. Prolong the life of your system and ensure you get the best return from your investment 

Reminders so you don't forget

It's easy to forget so we will send you reminders when your service is due, providing you with even more peace of mind.

Meet your legal requirements

It's a legal requirement to ensure your system isn't polluting the environment and failure to comply. could result in fines

Fast repairs when needed

Most repairs are done during a service or breakdown call out as we keep a record of your system and carry spare parts for your system with us.

Why use us?


Top rated customer service

We’ve built up a reputation for being friendly, professional and 100% reliable. You can count on us for excellent service.


We know our stuff

 Our 30 year proven track record of installing wastewater solutions speaks for itself. We're specialists when it comes to the installation, maintenance and repair of sewage systems



Integrity and honesty are core to what we do. We're a family-owned business and are known for being trustworthy and hard working.

            Contact us today for advice 

            0121 461 4861 

Useful information on Graf sewage treatment plants


Here are some frequently asked questions about the maintenance of Graf sewage treatment systems:

Can you service my Graf sewage treatment plant?


At Cotterill Environmental, we are accredited suppliers of maintenance and repairs of Graf sewage treatment systems. 


We provide services and maintenance for a range of sewage treatment plants by Graf. These include One2Clean, OneAdvanced and Klaro E Professional. The One2Clean model is a popular choice for wastewater management, and has many benefits. Only one tank and one chamber is required for the entire system, and there are no pumps required in the waste water.


There are also no electrical components in the waste water. There is a significantly lower amount of sludge in comparison to other sewage treatment systems, meaning the tank will need to be emptied less frequently. No concrete surround is required, only a gravel base and backfill, which makes the installation process easier.


These Graf One2Clean tanks are corrosion resistant and 100% watertight, meaning you’ll receive excellent value for money with this product due to its reliability and long lifespan. 


Instead of requiring multiple chambers to perform the treatment process, the Graf One2Clean tanks only need one chamber which performs the process in cycles. This saves space in excavation, and makes the product more compact and efficient. 


The OneAdvanced model has the power to detect low usage and set the tank to holiday mode, meaning you won’t waste energy in running it while you’re away from home. This model and One2Clean are also incredibly quiet, meaning that there will be no noise pollution when using this product. 


Graf sewage treatment plants provide an efficient and cost-effective solution to off mains wastewater treatment. 


Why choose Graf?


Graf has been providing water solutions successfully since 2007. They are a highly reputable brand, and their products have sold on a mass scale all over the world. They supply a wide range of products, from sewage treatment plants, to rainwater harvesting tanks and soakaway crates. Graf have won many awards, as their products are highly efficient and have innovative designs.

Why is it important to service your Graf sewage treatment plant?


It is very important to get your Graf sewage treatment plant regularly serviced for a number of reasons. 

1 - Regular servicing means that your product’s performance is being optimised. This means that any faults can be quickly and easily identified, and arrangements can be made with our engineers to fix them. Having your Graf sewage treatment plant regularly serviced gives you peace of mind that it is safe to use for another year. 

2 - Costly repairs can be avoided with regular servicing. Any issues can be quickly addressed, which will save you time and money in the future.


3 - The product’s lifespan will be extended if it is properly maintained. The Graf One2Clean sewage treatment plants come with a 2 year warranty on technology and a 10 year warranty on sewage reservoirs. Regular servicing will make your system last as long as possible. 

How often should you service your sewage treatment plant?

We recommend getting your sewage treatment plant serviced once a year for a domestic property, and between every six months to a year for commercial properties. Once on our system, our customers can opt into annual reminders for any maintenance services required. This gives peace of mind that your Graf sewage treatment plant will be well looked after. 

What areas do we cover?

We cover the whole of the midlands and can also work further afield depending on the drainage project. Areas in the midlands that we cover include: 

Birmingham (West Midlands), Coventry (West Midlands), Hereford (Herefordshire), Lichfield (Staffordshire), Stoke-on-Trent Staffordshire), Wolverhampton (West Midlands), Worcester (Worcestershire), Shrewsbury (Shropshire), Warwick (Warwickshire), Derby (Derbyshire), Leicester(Leicestershire), Oakham (Rutland), Lincoln (Lincolnshire), Nottingham (Nottinghamshire), Buxton(Derbyshire), Glossop (Derbyshire), Cleethorpes (Lincolnshire), Northampton (Northamptonshire), Tamworth, Sutton Coldfield, Solihull, Lapworth, Knowle etc.  

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