Diagnose Clogged Drain vs. Septic Backup or Failure

The drains in your building or home are draining slowly and/or frequently clog, and you have an onsite waste disposal system referred to as a septic tank system, the problem must be correctly identified. Many times, clogged drains and slow drains can be resolved by clearing the plumbing backup inside the building. But if it is a septic tank problem, you might be wasting your time and money trying to solve the wrong problem. What do you do?

Slow and clogged drains are commonly thought to originate in the drain-waste-vent system because this system is used frequently throughout the day, every day. However, it makes good sense to investigate and find the problem area first – as it might not be in the building.

Ben Franklin Plumbing in the San Francisco Bay Area recommends calling us for a professional and thorough evaluation of a plumbing problem. We are highly experienced in all drain vs septic field issues and affordable septic tank repair. But if you feel comfortable attempting a diagnosis, here are a few things you can do that will assist you in narrowing down the problem.

Plumbing Drain Noises

Believe it or not, plumbing drain noises can help direct you to the source of the problem. That “blub glub” noise from a drain where water is passing could mean a problem with:

• Partial drain blockage, forcing the water through a constricted area creating a hiss or blub sound.
• Drain venting problem. Inadequate (or completely missing) plumbing vents can create a gurgling sound. There is not enough free flow due to trapped air or a partial vacuum. If you hear gurgling at the sink or shower drain only when a nearby fixture is being used, such as a toilet flushing, the drain venting may be the culprit.
• Plumbing drain noises that don’t impact functionality. Some pipe materials transmit noises more readily that others. Plastic drain piping sounds different than cast iron piping. The solution is proper sound insulation, but you should use an experienced plumber to track down the sound or sounds and apply the proper type of insulation at the right points.
• “Unusual solutions” amateur plumbing. It can happen that unqualified handymen attempt to fix a plumbing situation with non-standard solutions like running waste lines inside the building at odd angles that fight against gravity and result in noise and pools of non-flowing water that accelerate corrosion or leaks at joints. It can also create a sewer gas smell that is noticeable at the fixture.

If a single fixture in the building is sluggish or clogged and all the others are operating fine, the problem is most likely NOT your septic tank. It is a clog in the waste stack or soil stack (drains from sinks or toilets) and that is the first area to address.

If your entire home drains slow or is clogged or if waste is backing up into the lowest elevation plumbing fixtures, suspect the septic tank or field.

Septic System Issues

You may think of your septic tank as a singular element, but it is actually a system that involves waste pipes, absorption fields into the earth and the tank itself.

• Absorption fields. Does your problem occur during rainy weather? If so, you may need a professional inspection. Your septic tank absorption field should be about five feet below the top of the high water table. If this field is improperly installed, it may be that the field is flooded and cannot take on the outflow from the tank. If this is the case, you may be contaminating the local groundwater with pathogenic materials that flow from the tank. This is definitely not a DIY fix. Contact Benjamin Franklin Plumbing in the Bay Area and we’ll send out an experienced and highly trained septic tank system pro to evaluate your situation and suggest a cost-effective solution.
• When an absorption field fails, there are only two options: build a completely new drain field or add more branches to the existing field to increase capacity.
• The sludge in the tank can form a layer of biodegradable material below the pipes, preventing the water from leaching into the ground. The standard for septic tank maintenance recommends pumping out the tank every three years so that this doesn’t occur.
• Septic tank has been pumped but backups still occur. This may indicate that the pipes from the fixtures that flow to the septic tank are blocked. The first thing to do is have these pipes professionally cleaned out. Our plumbers can run a camera down the line to locate any blockage due to sludge, breaks or cracks in the pipe, or roots. This procedure may also determine if the septic tank is functioning correctly.
• Isolating the problem as being between the building and the septic tank, you find standing water in the pipe between the two. In addition to causes noted above, the drain pipe may be collapsed from shifts in the earth, power snake damage or corrosion. Often in cases like this, the tank scum (top) and sludge (bottom) levels are above their limit and the septic tank must be pumped out immediately.
• Lines are clear, and the septic tank has been pumped but there is still a backup into the building. This is usually a drain field issue. The effluent sludge in the tank rises and leaves the tank and flows into the drain field, plugging the field and causes the flow from the tank to back up. This can happen when the field is improperly pitched or laid out and it then becomes a magnet for rainwater and ground water. As a result, the waste flow is prevented from properly leaching into the field as it should.
• The septic tank backs up during a party or when guests are visiting or staying over. This is usually a situation where the septic system could not accommodate the additional multiple gallons of water generated by the sudden rise in facilities use. It is a high wastewater volume issue complicated by a tank that was not empty enough to accommodate the extra input. Very high wastewater volume over a short period of time can cause a flood in the drain field which then leads to a backup of the waste line into the house.