We offer full surveying services for off-mains drainage systems, so you know what you’re dealing with.


We create fully bespoke drainage solutions, giving you peace of mind that everything is suitable for your site.


We install your new drainage system with as little disruption to you as possible, while keeping you informed.


We regularly maintain drainage systems so you never have to worry about them breaking down.

Avant Installations

Whether you’re looking to install a new domestic sewage treatment plant or are confused by the soakaway on the property you’re looking to buy, Avant Installations can help you. We are specialists in off-mains drainage systems, with years of experience surveying, designing, installing and maintaining these products.

We can complete major jobs – such as creating and fitting an entirely new, bespoke drainage system for you – as well as small projects as simple as scheduling your septic tank in for regular maintenance. Whatever your needs, Avant can help you.

We understand that not everyone knows the difference between a WTE and a Klargester sewage treatment plant, so we’re committed to making your project as easy as possible for you, minimising disruption and stress. Contact us for more detail on how we can help you with your drainage needs.

Avant Installations Projects

Here are just a few of the projects we have completed for our clients.


At Avant Installations, we have been specialising in off-mains drainage systems since 2010. We believe that there are a lot of advantages to owning a property with this kind of drainage, so we are committed to making sure it is always beneficial for our clients. We have always aimed to exceed our customers’ expectations in this regard.

With a firm understanding of construction practices and how off-mains drainage systems are required to function, we are able to offer a complete service that covers the entire lifecycle of our products. This ranges from pre-purchase surveys to the design and installation of entirely new systems, and we will be there carrying out regular maintenance throughout their working lives.



The survey fee was definitely a fee worth paying resulting in negotiating a £5,000 reduction on the property , something I would have definitely missed if not having the report. Once again thanks for your professionalism and I would have no hesitation in recommending your services.

Carl Seymour

The installation was carried out in a well planned manner. Chris and Jamie proved to be knowledgeable and very helpful right from the start. I am happy to recommend Avant.

Mr Hall. (Coventry)

Despite the horrendous weather all the work was completed on time and at the price quoted. Very pleased with the service.

MR & Mrs Roading. (Leek)

Super Service, Chris and his team were very helpful throughout the whole process.

Miss R Cartwright. (Bolton)

It was a real pleasure having you and Jamie working at our property and it is clear that you both get on very well which helped to make the whole upheaval of what was a fairly major undertaking exceptionally stress-free. The job itself was completed on time, on budget and to a very high standard including tidying up the garden afterwards and I can’t praise you both enough for your professionalism, hard work, helpfulness and willing attitude.

Ewan J Watson MSc, RAF Squadron Leader (Retd)