Rainwater Soakaway’s and French Drains
What is a Rainwater Soakaway?
A Rainwater Soakaway is a drainage solution for a home or property that does not have access to public sewers, drains or storm drains. The Soakaway takes the rainwater collected by your guttering etc and allows it to drain off away from your property to avoid subsidence issues and puddles on your lawn.
How does a Rainwater Soakaway work?
Based on the volume of rainwater you are likely to collect a Rainwater Soakaway is designed specifically for your needs. The Soakaway itself is essentially a large hole filled with rubble or soakaway crates. The Soakaway takes the rainwater well away from your home via a downpipe. The water is then allowed to dissipate into the surrounding ground.
What problems occur if my Rainwater soakaway becomes blocked or overflows?
If the rainwater cannot dissipate in the Soakaway then the rainwater cannot escape. Puddles will develop at the base of the downpipes which originate from your guttering. Gutters will overflow and possibly collapse. Depending on the issue or problem with the Soakaway system the soakaway field itself may become waterlogged. It is important to note that while water will gather at the base of the rainwater downpipe, it is not the downpipe causing the problem. The issue is almost certainly further on in the system. What you are seeing is caused by the backing up of the discharge caused by a blockage.
Why do I need a Rainwater Soakaway?
Keeping the rainwater away from your domestic or commercial property is important for the following key reasons. Firstly, a soakaway helps to prevent the onset of damp in your property by moving the water away from the property. Secondly, by moving the water away it helps to prevent possible subsidence issues with your property due to the foundations being compromised. Thirdly, the soakaway helps prevent waterlogging and puddles developing in your garden making it a more useful and enjoyable space.
What is the cause of Rainwater Soakaway problems?
We like to think of the Rainwater Soakaway as a system made up your guttering etc, the pipe section to the soakaway and the soakaway itself.
We like to design and install Rainwater Soakaways to incorporate filters in each of the main sections of the system. This helps to prevent the most common rainwater soakaway problems. Any issue caused by one of the filters in the system being blocked with debris is easily fixed.
Soakaways inevitably fail, it is in their nature this is the other main cause of Rainwater soakaways having problems. This may be due to the soakaway crates or void being filled with sludge or debris. This means the water is no longer able to dissipate or drain away.
Another often misunderstood reason for a Rainwater Soakaway failure is that the simply the soakaway is too small for your needs. It has been incorrectly designed. This will mean that when the input of water exceeds the capacity the soakaway is able to deal with it will back up and flood.
How is a Rainwater Soakaway designed and installed? How to build your own Rainwater Soakaway?
We obviously would not recommend building your own rainwater soakaway in the UK unless you have had some engineering or ground working background. The key rules and steps in the design process you should take are below.
A Rainwater soakaway is designed by firstly calculating the likely amount of water that will be needed to be dissipated by the soakaway. This is crucial.
You will then need to consult with the relevant legislation and if necessary building control. Please see the regulation question below.
You need to consider where to put the soakaway, the following points need to be considered.
- The Soakaway needs to be downhill of your property. Water runs where gravity tells it to. This can be overcome by a deeper soakaway pit but is crucial.
- You need to test how porous the soil is in the desired location. This is achieved by carrying out a peculation test, please see this link. You then need to take the amount of water you calculated as needing dissipating and divide it by the relevant results of the peculation test. This will tell you how big the soakaway needs to be.
- Check again the site chosen adheres to the relevant legislation.
- Remember your filters in the design.
- Dig the soakaway hole. Line the bottom with porous stone. Then an appropriate layer of Rainwater soakaway crates or rubble.
- Then construct the downpipe linking the house and guttering to the soakaway.
We appreciate this a basic guide but it gives you a feel. If you would like expert advice or for us to undertake the installation call us for a free visit and quote.
How to clear a blocked Rainwater Soakaway?
If you are technically minded check and clean the system’s filters, replace if necessary. This is the main cause of rainwater soakaway problems. If there are no filters then a bigger problem is likely.
If the soakaway has failed due to becoming filled with debris or changes to the water table etc you will need to replace it. This will require a dig up and re-install of the soakaway pit.
What are the regulations and legislation related to the installation of a Rainwater Soakaway?
We recommend you read the relevant parts of this document which sets out the relevant 2010 Building Regulations. The Key points are below:
- You need to find out whether your site or domestic home is in a Groundwater Source Protection Zone.
- You should dig a Trial Site Assessment Hole to find out whether the bedrock or water table ever comes within one meter of the rainwater soakaways pipe bottom. Commonly soakaway sites in the UK fail this test.
- As discussed above in the design and install question. You must carry out a percolation test to ensure the excess rainwater will dissipate into the soil at an acceptable rate. We recommend this be undertaken in conjunction with a calculation of the likely volume of water your site or domestic property is likely to produce.
- The stone or other filling materials must completely surround the pipe or soakaway crates and come to at least 100mm above it. Another layer must be placed on top.
How do I maintain a Rainwater Soakaway?
Check and clean all of your guttering on a regular basis, especially after the autumn leaves have come. Check and clean the filters in your Rainwater Soakaway system, if you do not have any, install some.
The soakaway itself is largely left untouched. The important thing is to stop the garden waste from getting into the soakaway system.
Can I empty Waste Such as Sewage Water from my septic tank into a Rainwater Soakaway?
No, firstly this is illegal and will result in prosecution if you are found out. Secondly, It will clog the drainage system and eventually result in the soakaway failing.
Do Rainwater soakaways work in clay soils?
Soakaways only work if the water has somewhere to go. A high water table or clay soil can prevent this. You will need a site inspection and percolation test to see if a soakaway is an answer. There are alternative solutions. Please get in contact with us.
What is the difference between a Rainwater Soakaway and a French drain?
A French drain is essentially a drainage trench which then drains to your Rainwater Soakaway. A French Drain is used to combat areas where surface water pools either after heavy rain or due to poor drainage. Classically they are employed to move water to away from walls and driveways
Rainwater Drainage/ French Drain install and problems
Who we are
Expert Engineers who specialise in Septic Tank and Soakaway replacements as well as Sewage Treatment Installations. We are based in the New Forest, Hampshire but operate across the South Coast as well as Wiltshire, Somerset, Devon, Sussex, Surrey, Oxfordshire and Berkshire.
New Forest Philosophy
As we have said Homeseptic is based in the New Forest. A great location in between the cities of Southampton, Salisbury and Bournemouth. We are a group of good friends who grew up together in the area. Individually we all have grown tired of the way other Drainage firms are run. As a result, this is why we set up Homeseptic.
We want to actually put the customer first and turn up to do a great job that we can be proud of. Unfortunately, this is not the case in the market, with most companies pressuring their workers to sell unnecessary works on a visit. Due to this, we offer upfront quotations with any variations discussed before we start work.
We are honest hard working professionals, which we hope you will agree with. As a result, it will certainly not turn up in flash sales vehicles and give you a load of chat and then do a terrible job. Our team will come with the job in mind and the aim of giving you the best value we can in order to facilitate a quality installation.
We cover all of Hampshire, West Sussex, Dorset, Somerset, and Wiltshire. Please get in touch and see what you think.