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Selfbuild Off Mains – Your 6 step Checklist


STEP 1 – Secure Plot 

Embarking on a self-build project can be daunting, so it’s vital to work through the process systematically to make sure nothing gets missed. An area that many self-builders don’t properly consider until the project is underway is wastewater treatment and rainwater harvesting.
Approximately 25% of self-build plots are ‘off water mains’, therefore it is important to know what your options are as early in the process as possible. If you’re choosing between multiple plots, don’t be put off by a lack of connection to mains drainage. An ever-increasing number of houses in the UK successfully rely on independent wastewater treatment systems and technology has come a long way since the days of traditional cesspits and septic tanks!


Is the plot rural or urban?
Is the plot connected to mains drainage?
Will the plot have a mains water connection?
Is the plot near a river or stream?
Which system will meet your needs, and local authority requirements, the best?


Is your plot connected to mains water?
What do you want to use your rainwater for?
Which kind of system will meet your needs the best?
Will a gravity or direct system best meet the plot’s needs?

STEP 2 – Designing your dream

You’ve decided to go ahead with a self-build project including an independent water treatment system – congratulations! You are part of a growing movement in the UK, breaking away from the constraints of existing infrastructure. A significant, and growing, number of houses in the UK successfully rely on independent wastewater treatment and rainwater harvesting systems.
Don’t be intimidated by the decision to ‘go it alone’. With a wealth of information at your fingertips, going ‘off-mains’ can be done simply and without any extra stress. And with all the other pressures a self-build project brings, less stress is a good thing!


How many bedrooms will your property have?
Is your property to be used as a holiday home?
Is your property to be used as a guest-house?
What would be the ideal stage to install this type of equipment?

What is the total area of roof space for capturing rainfall?
What are the implications of differing systems on your build?
What would be the ideal stage of your project to install this type of equipment?

STEP 3 – Architect Appointed 

Once you’ve appointed an architect you should discuss your wastewater treatment and rainwater harvesting requirements with them in depth. For your convenience, this datasheet can be printed so that you have all relevant information easily to hand. Once you’ve decided upon a system, there are a number of sources you may need to consult before proceeding:
• Your local environmental agency (EA, SEPA, EPA, NRW or DoE NI)
• Environment Agency Pollution Prevention Guidelines PPG4
• British Standards 6297
• European Standards BS EN12566
• Building Control Regulations 2000 Part H Drainage and Waste Disposal, 2002 edition
• British Water Flows and Loads – 3

Has a percolation test been carried out to determine ground conditions?
How far in advance do I need to order equipment?
Can large trucks gain access to the site?
Will I have suitable unloading equipment available?
What are the running costs of comparable wastewater treatment and rainwater harvesting systems?

STEP 4 – Planning approved
Once the relevant local authorities have approved your self-build plans, a building schedule can be put in place. This is the time to start thinking about procuring the necessary equipment and materials for the build. Wastewater treatment and rainwater harvesting are a crucial part of your project, so it’s worth giving the choice of system careful consideration.
You should consider installing your wastewater plant during the building phase of your project, especially if you’re intending to live on site for the duration of the project. Plants can be connected to your temporary accommodation until your new home is complete.

Have I fully discussed my options with my architect?
What is my predicted start date?
What are the implications of differing systems on your build?
What would be the ideal stage to install the equipment?
Have I received the necessary wastewater treatment approvals from all relevant authorities and agencies?
What are the installation costs of equipment?
What are the on-going operation and maintenance costs?

STEP 5 – Builder selected

Now that you have appointed a building contractor, the real excitement and activity begins! Local builders have immense practical knowledge, so be sure to take advantage of this invaluable source of information.

Who will buy these products?
What will be the best stage of the project to install this equipment?
Have you discussed the ideal location for optimum plant performance with your builder?
Will your contractor be able to offload products on your behalf?

STEP 6 – Construction started
Congratulations – your self-build is finally under construction. The weeks, months and possibly even years of planning have all been building up to this point.

Need help or guidance with picking your Sewage Treatment Plant or Rainwater Harvesting System?
Contact our team today – click here