Home Buyers Drain Surveys | DrainBlitz

Pre-Purchase Drainage surveys – Don’t Buy a Property Without One!

If you are buying a new property which is connected to a septic tank, or any other off mains drainage system, a thorough inspection of the system at the property could save you thousands of pounds.  A typical house buyers survey will only take a very basic look at a property’s drainage system.  Often this simply involves lifting manholes to see if the drains are flowing.  In many cases, the surveyor will note that no obvious problems were spotted, but that it would be advisable to get a more thorough drainage survey undertaken.Here at Drain Blitz we get many calls from property owners who didn’t take this advice, and who unfortunately in a matter of months become aware of problems within the property’s septic tank which can be very costly to put right.  This doesn’t necessarily mean that the previous owners were even aware of any of the problems though.  This is because some problems underground can take months before they’re noticed above ground.  All this makes it more important that a pre-purchase drainage survey is undertaken, because a quick look see is rarely enough to know if there are any issues.We understand that once you have your heart set on a new home, the last thing you want to find out about is any potential issues – particularly relating to drainage, which is not really a subject that anyone wants to deal with!  But a property’s drainage system is no less integral than its foundations or its roof, and your property is the biggest investment you will ever make, so don’t make a move without knowing exactly what you’re taking on.  If there is trouble brewing underground, it doesn’t need to be bad news.  A thorough inspection will let us know whether there are any problems – and if there are, we can guide you as to exactly what might need to be done.

What’s involved in a Home Buyers Drain Survey.

Our Certified Drainage Surveyor will provide you with easy to read and understand reports which will include:


What if the house is non-mains drainage?

  • Confirmation on whether the septic tank is the right size for the property (as per Building Regulations 2010 Part H – don’t worry if you’ve not come across that before, we’ll explain it all)
  • Whether the system is compliant with current legislation and the new General Binding Rules due in 2020 (don’t be put off by all the legislation talk, that’s why you have us on your side!)
  • Any damage found within the tank such as cracks or splits in the walls, or tree root damage
  • Confirmation that any dip pipes or baffles are in place – these are the things that ensure that the septic tank can separate out the waste, and prevent any of the solid items from leaving the tank (which causes all sorts of soakaway problems.)
  • Any recommendations if problems are found.

We’ll also give you a disc with a copy of any CCTV footage we undertake of the drainage system and a full coded report.

What is a percolation test?

Soakaway systems can be used to take the wastewater from either a septic tank or a sewage treatment plant.  It’s a network of perforated or slotted pipework which allows the waste water to percolate safely through the ground without causing pollution.A percolation test is used to decide whether the soil at a property is suitable for a soakaway system (also known as a drainage field).  If the ground is suitable, a percolation test will then decide how big a soakaway system needs to be.The percolation test itself involves digging three test pits in ground where you are planning to install a soakaway system, and measuring the speed at which the water drains out of the pits. The test is usually carried out over two days.Here’s a picture of a test pit for a percolation test our team have recently undertaken.  You’ll notice the measuring stick that has been used, which helps the engineer to time the speed at which the water drains (or percolates) away.

Do I need a percolation test?

If you are thinking about installing a new soakaway system or replacing an existing one, then the simple answer is yes. If a soakaway system or drainage field is installed in ground which isn’t suitable, or if it’s not the right size to take the wastewater from the property connected to it, then you’re likely to get soakaway problems quite quickly.The Drain Blitz team can manage everything for you – from undertaking the test itself, through to producing a detailed report outlining exactly how the soakaway system should be designed. Then we can install the soakaway for you.

What if a percolation test fails?

A percolation test provides a Vp reading, which measures the speed at which water drains into the ground through the test pits. For the ground to be considered suitable, the reading must be between 15 and 100. Sometimes, percolation tests can fail right from the start, or it might be that the reading sits outside of this acceptable level. If this happens, our team will work to undertake a thorough assessment of all the options available to you.

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