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Septic Tank Problems

Molloy Precast

If you are having difficulties with your Septic Tank, the decision tree below helps find the issue with your septic tank, and points you towards possible solutions.

Septic tank problem

Troubleshooting problems with the on-site wastewater treatment system

Problems with septic tanks are generally noticed when toilets and other household utilities stop functioning properly or if the septic tank begins to overflow. The first thing to check when this happens is if the pipes leading to the septic tank are blocked. If the water levels in the septic tank are normal, then there is a blocked or collapsed pipe somewhere. If this is not the case there is either something wrong with the septic tank or the percolation system. Listed below are some common problems and some solutions, it is recommended that where a complicated problem is encountered the homeowner consult with a competent person/company.

If the problem only occurs occasionally:

Check if there is rainwater entering the system. To do this, in dry weather pour water into the rainwater pipe system (gutters/manholes), check if it enters the septic tank. Solution – A Check for surface water entering the system via tank lids or manholes during wet conditions. Solution – B If there is no surface water or rainwater entering the system, it is likely that the percolation system is starting to break-down, consider replacing it with a new one.

If the problem is consistently occurring all year round:

Investigate the type of percolation system, if it is a soak pit, it is likely that this has failed and may need to be replaced. Soak pits are not long term solutions for wastewater disposal. Traditionally these were used to distribute the effluent from a septic tank into the ground. More often than not these soak pits give trouble; there are several reasons why this might happen, some of the more common reasons are: A soak pit is not designed to treat wastewater, it does not have enough surface area for an adequate amount of biofilm to grow, or have a ventilated oxygen source to ensure appropriate treatment of the wastewater. This can cause a build-up of substances which will reduce and eventually stop soakage into the ground, causing the septic tank to back-up. This is generally the problem if a soak-pit fails after a number of years of good operation. Solution – C Often times the land taking the effluent does not have good soakage properties, causing the soak pit to fill and hence the tank to back-up, generally this is noticed straight after the system is installed, however, this problem can combine with the previous problem and cause trouble after a few years of operation. Depending on soakage properties two separate solutions can be applied. If the land has good soakage solution C could be employed, however, if the land has poor soakage solution D might be required. The underground water table could be high enough to render the soak pit useless, i.e. the tank can never empty as it is flooded with ground water. In these cases the groundwater is directly polluted by raw wastewater. This might only be a seasonal problem, i.e. long periods of wet weather. Solution E

If the wastewater is pumped from a secondary treatment system or septic tank, check if the pumps are working properly, or if the power supply is working. Solution – F Some problems with on-site wastewater treatment systems which might arise do not directly impact on the functionality of household utilities. These problems can be associated with the septic tank or the percolation system. These issues often cause pollution unknowingly to the homeowner.

Unseen problems associated with septic tanks

Over time old tanks can leak directly into the ground, this can be the result of poor workmanship, subsidence, root intrusion, or old age on a block work tank. This can occur unknowingly to the homeowner. Solution – G If the septic tank is not regularly de-sludged, it will start to discharge solids and FOGs into the percolation system. A percolation system is not able to handle this type of wastewater and will eventually fail. Solution – H Ensure that the inlet and outlet tees are on the inlet and outlet pipes of the septic tank. If missing FOGs flow into the percolation system and will eventually cause failure. Solution – I Check if the septic tank is suitable for the occupancy of the household. Solution – G or J

Problems associated with a percolation system

Visual signs of ponding of wastewater around the tanks/percolation system, this is often the result of a failed percolation area. Failure can be caused by: Release of excessive quantities of solids from the tank, often caused by a lack of tees in the tank or failure to de-sludge the tank. To ensure this problem does not happen again check if the size of the septic tank meets the requirements. Solution – C combined with J, G, or K A high water table. Solution – E Percolation system is too small to cope with the influent entering it, due to rainwater/surface water ingress or the volume of wastewater entering it. Solution – C Poor soakage in the ground preventing water from escaping, Solution D Signs of excessive growth in drains/ streams near the wastewater treatment system Check for pipes discharging wastewater into the water course if present solutions include – C Check the distance between the percolation system and the water course, there could be underground seepage between these, this distance should be no less than 10m. Solution – C

Possible solutions

A) divert rainwater pipework away from the septic tank into a separate soak-pit, Potential costs – minor, some civil works may be required

B) raise lid/manholes over surrounding ground to prevent surface water ingress or create a watertight seal where water is getting in – Potential costs, minor, some civil works may be required

C – Construct a new percolation system – Potential costs, percolation kit, stone and civil works, depends on size required, between €1,500 and €3,500 D – Replace Septic tank with a secondary treatment system and construct a polishing filter -Potential costs, Secondary treatment system percolation kit, stone and civil works, depending on size required, between €6,500 and €8,500 E – Replace septic tank with a secondary treatment system and construct a raised polishing filter – Potential costs, Secondary treatment system percolation kit, stone and civil works, depends on size required, between €6,500 and €12,500 F – Replace faulty electrical equipment or check fix electrical problem – Potential costs, new equipment and labour, €50-€500 G – Replace septic tank with a new one, Potential Costs – Septic tank and civil works, €2,000 H – De-sludge Septic tank, Potential costs – approximately €250 I – Install or Replace inlet and outlet tees, Potential costs – minor J –Install a second tank upstream/downstream of the existing tank, potential costs – between €1,000 and €2,000 K – install a septic tank effluent filter, this filter slows down the flow from the septic tank, resulting in the capture of solids (Requires regular washing) – Potential costs, minor