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Soakaway problems and their causes solved by Homeseptic.

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Soakaway & Drainage field Problems and their causes

 Get in contact with us on 0800 3101092  or via our Contact Page
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How do you know if your Soakaway is having problems?

The most common cause of a failed Soakaway is some form of blockage, the second most common cause of a failed Soakaway is a  poor installation; notably when a Percolation Test has not been completed before the installation is carried out. When you get a quote for a new installation if the company does not mention carrying out a Percolation test then do not use them, you must also ensure that the works are signed off by a Building Control Officer. 

A blockage can be caused by many factors, which we discuss below. However, when a Soakaway becomes blocked, and it will inevitably at some point (all Soakaways fail), you will certainly know about it.  Imagine running a bath and leaving the plugin, this is essentially what will happen. The water and waste will have nowhere to go and so will back up. The warning signs are many but inevitably take the form of bad odours and or the pooling or collection of water in previously dry areas. You will also likely see baths, toilets and appliances draining less quickly and potentially overflowing. If you have a Septic Tank, Sewerage Treatment Plant or Cesspit in the system they will fill up and overflow.

What is the difference between a Septic Tank, Drainage Field and a Soakaway?

A soakaway is an underground area where liquids are allowed to seep away into the surrounding ground. Up until 2007, the majority of domestic sewage systems discharging to the ground did so using a soakaway. From 2007 Building Regulations changed. This meant, that from this point any new or replacement discharge made had to do so via a Drainage Field. A Drainage Field is essentially a soakaway designed, sized, and constructed in a specific way. Please see our guide for more details.

A Septic Tank is a watertight container with an inlet and outlet, it lets water in and out The outlet is slightly lower than the inlet. Both the inlet and out have a T-piece on them. The T-pieces hold back elements of the solid content of wastewater, stopping it from leaving the tank. The Septic tank is a separation and storage device.

What is the function of a Soakaway?

The function of a Soakaway is to allow the liquid entering it to dissipate/escape into the surrounding ground. Soakaway problems are caused when the amount of liquid entering the Soakaway is greater than that being released. This causes the ground to become boggy or saturated. If all of the wastewater entering the Soakaway cannot escape the system will also start to back up through the pipework. The system will start to discharge at any weak points in the system, generally tank and manhole lids.

When used with a Sewerage Treatment Plant the function or job of a Soakaway is different. Its job is to primarily distribute the treated output of the tank. This will prevent any areas of soggy or waterlogged garden.


Soakaway Problems, Failed, Broken or Blocked

A boggy soakaway or drainage field

A Blocked, Failed, or Broken Soakaway or drainage field

The adjacent picture shows the most obvious sign that something is not working with your Soakaway. A big puddle of standing liquid where your drainage field/ Soakaway is. Clearly not much is Soaking away here! 

In this particular example, the problem with the Soakaway was a poor installation. Both are poorly planned and installed. The main problem was that no account was taken for the winter water table. When the winter rain came the water table rose to the level of the soakaway. This meant there was nowhere for the discharge from the system to go.

There was no way of repairing or replacing the adjacent soakaway in or around its current location. The water table was too high, which a percolation test of the ground conditions would have shown. Clearly, a percolation was not undertaken and waste water was flowing directly into a brook. The owner was lucky that the Environment Agency had not seen what amounted to an open sewer. As you will recall a septic tank does not treat the waste water, so it combined with suspended solids was being emitted. With the upcoming legislation change, 1st Jan 2020, the Environment Agency will have a much stronger mandate.  

What difference would a Sewage Treatment Plant make?

Sewage treatment plants have an internal treatment system. Therefore, if there is a soakaway failure the problem is not so acute. The Environment Agency, providing the treatment system is well maintained and tested wouldn’t have such a big issue. In a septic tank system, the soakaway is the treatment system.

How do you know if your soakaway has failed?

If your Soakaway has failed then the wastewater will have nowhere to go. The system will quickly fill up and prevent further wastewater from entering the system. If the problem is not fixed any holding point in the system will fill up and overflow. Also inspection chambers, open drain points will overflow. Any additional waste water you attempt to put into the system will have nowhere to go. This will lead to overflowing toilets and drains, broken appliances and some pretty bad smells.

A Soakaway is classified as failed if it cannot be repaired and requires a new installation. Soakaways by virtue of their function and design will eventually fail. Many of the symptoms of a failed Soakaway are similar to a blocked repairable Soakaway. To identify a failed Soakaway we would inspect the current Soakaway and the problems it has. Given our years of experience, we can normally tell pretty quickly if the Soakaway is repairable. To make this call yourself without experience is tough. Check the installed filters to see if they are blocked. Check that the system is discharging to the Soakaway if it is not then the problem is not your Soakaway. Excavate a section of the Soakaway, does water then flow freely into the excavation hole. If it doesn’t then the problem, blockage or failure is likely in the Soakaway system. If the water does flow freely and the soil is black and pungent then failure is likely.

What are the main causes of Soakaway problems?

  1. Flushing inappropriate things down the toilet – baby wipes, nappies, tampons etc. These items are likely to cause problems before they reach your Soakaway but will obviously cause a blockage. With modern Sewerage Treatment Plants, these items will cause the failure of the tank and are very costly!
  2. Not regularly emptying your Septic Tank of Sewerage Treatment Plant. While this may initially seem like a money saving idea it will cost you more in the long run.
  3. Tree and plant roots growing through the pipes of the soakaway or anywhere in the system. This can prevent the wastewater passing through the soakaway. Tree roots are especially harmful. 
  4. Collapsed or displaced pipes in the soakaway. This can be caused by natural movements in the soil or say by driving a heavy car etc over the drainage field.
  5. Damage to the dip pipes or baffle within a septic tank can cause a soakaway to become blocked. 
  6. Poor maintenance of the Soakaway filters. These will require high-pressure water to clean. 
  7. Failure or problems with your Septic Tank or Sewerage Treatment plant which allow untreated waste to enter the system. With a Septic Tank system, this is less problematic but will cause permanent damage in the long run. Soakaways for Sewerage Treatment plants are not designed to deal with waste.
  8. The biggest cause by far is an initial poor Installation. The common signs of a poor installation are no filters installed or the Soakaway being too deep. If the Soakaway is too deep then Aerobic digestion and processing will be impossible.
  9. As well as a poor installation another common problem is poor planning by cowboy firms. Many firms do not carry out proper percolation tests. This means they have no idea how quickly the intended area will drain water. Also if the area is suitable for a Soakaway drainage field at all.


Soakaways that are broken, fail or have problems

This video shows what happens when a septic soakaway system fails.

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