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SEPTIC SYSTEM INSPECT DIAGNOSE REPAIR
SEPTIC CARE INSTRUCTIONS
SEPTIC D-BOX INSTALL REPAIR
SEPTIC DRAINFIELD FAILURE DIAGNOSIS
SEPTIC DYE TEST PROCEDURE
SEPTIC FAILURE SIGNS
SEPTIC INSPECTION & TEST GUIDE
SEPTIC LIFE EXPECTANCY
SEPTIC SUPPLIES & PARTS
SEPTIC SYSTEM DESIGN ALTERNATIVES
SEPTIC SYSTEM DESIGN BASICS
SEPTIC SYSTEMS, HOME BUYERS GUIDE to
SEPTIC SYSTEM SAFETY WARNINGS
SEPTIC TREATMENTS & CHEMICALS
SEWAGE BACKUP PREVENTION
SEWAGE EJECTOR / GRINDER PUMPS
SEWER GAS ODORS
SEWER LINE REPLACEMENT
SINKHOLES, WARNING SIGNS
SOAKAWAY BED FAILURE DIAGNOSIS
SULPHUR & SEWER GAS SMELL SOURCES
TOILETS, INSPECT, INSTALL, REPAIR
TRAPS on PLUMBING FIXTURES
TREATMENTS & CHEMICALS, SEPTIC
VIDEO GUIDES: Septic Videos
WATER CONSERVATION MEASURES
WATER SOFTENERS & CONDITIONERS
WATER SUPPLY & DRAIN PIPING
WATER, WELLS, WATER TANKS: TESTING GUIDE
WASHING MACHINES & SEPTIC SYSTEMS
WASTEWATER TREATMENT BASICS
WINTERIZE A BUILDING
Septic tank tank leaks are one of the things to check for during a septic tank inspection. Here we explain where and why septic tanks might leak, why surface water or runoff leaking into a septic tank is bad, and why septic effluent leaking out of a septic tank can also be a problem. We explain why pumping a flooded septic tank does not usually fix anything. Leaks in either direction, into the septic tank or out of the septic tank can be a problem.
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Our page top photo shows water ponding at the connection of a sewer line to a septic tank. Because this sewer line runs downhill from the house to the septic tank it was particularly good at collecting surface water and aiming it all at the septic tank entry port. Because the sewer line was not sealed at the tank, water entered and flooded the septic tank and drainfield.
See SEWAGE LEVELS in SEPTIC TANKS for details on normal and abnormal levels and what they mean.
Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted. Use of this information at other websites, in books or pamphlets for sale is reserved to the author. Technical reviewers are welcome and are listed at "References." This is a chapter of Inspecting, Testing, & Maintaining Residential Septic Systems an online book on septic systems.
Where do Septic Tank Leaks Occur
Our photo shows concrete poured around a waste line entering the septic tank. You can see that just as the concrete pooled in this location, the trench dug for the sewer line would, in wet weather, collect and aim a large volume of water into the septic tank.
You can reduce the chances of water leaking into a septic tank by making sure that roof runoff and surface drainage are directed away from the septic tank as well as the drainfield.
Leaks out of the septic tank prevent testing the septic drainfield
Leaks out of the septic tank can occur if the tank has a hole (for example a rusted-out metal septic tank) or if a concrete, fiberglass, or plastic tank is cracked or damaged. A leaky septic tank means that effluent may not be properly treated since it is not reaching the drainfield.
A leaky septic tank also means that a septic loading and dye test to attempt to check on the condition of the drainfield may fail to work. Particularly if the septic system has been unused for some time, and if the leak is near the bottom of the septic tank, the liquid level in the tank will drop very low. The result is that a normal septic dye test volume will simply be filling up the septic tank rather than pushing water out into the drainfield.
In turn this condition means that the septic test could not test the function of the drainfield. The risk is that new owners moving into the property will very quickly discover the bad news that not only has the septic tank got a leak but the drainfield may not really be functional.
A septic tank that is not in use and leaks out may also produce solidified scum and sludge that collect low in the septic tank or on its bottom - making septic tank cleaning extra difficult.
If there is a port to permit safely looking into the septic tank before an inspection or test, be sure to check the sewage level in the tank.
Leaks into a septic tank can flood the tank and drainfield
Leaks into the septic tank can occur if ground water or surface runoff are directed towards the septic tank or pipes that carry sewage into the tank (or effluent out of the tank). Any opening that permits surface runoff to enter the septic tank risks flooding the tank. In rainy weather the result can be a water overload in the septic tank, reducing the level of treatment in the septic tank.
Perhaps more of a problem, the same water running into the tank may also push its way into the drainfield, flooding the septic drainfield. If extra volume of the water entering the septic tank also prevents adequate settling time for sewage entering the tank then an excessive level of suspended solid waste may be forced of the septic tank and into the drainfield, further reducing the life of that component.
Leaks into a septic tank can also occur if the drainfield is so flooded that water is flowing backwards through the drainfield piping and back into the septic tank through its outlet.
Pumping a Flooded Septic Tank - Does that Fix Anything?
Pumping the septic tank won't fix any of these flooded septic tank conditions. A septic tank is normally always "full" to just below the septic tank outlet opening.
But pumping a flooded septic tank might be performed for the following reasons:
In our OPINION, if the septic tank floods once in 20 years, under exceptional conditions, no design changes or repairs may be needed other than cleaning the septic tank when floodwaters subside. But if this condition happens frequently, the septic system is unsanitary and may be a health risk to the building occupants or its neighbors.
At TANK INSPECTION PROCEDURE we describe how to inspect septic tanks.
See MEASURE SCUM & SLUDGE for a detailed description of how we measure the thickness of septic tank floating scum and bottom sludge levels.
See SEPTIC TANK LEVELS of SEWAGE for a discussion of the normal levels of sewage found in a septic tank.
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