Septic System Backup: Tank vs. Drainfield

There are fewer problems in your home that can be more aggravating and disgusting than a septic system backup, and unless you can pinpoint the location and cause, they can be troublesome to clear. A well-maintained system should work worry-free for many years, but proper maintenance requires a great deal of knowledge and discipline. One of the major causes of a backup is failing to have the tank pumped out on a regular schedule, but even with regular pumping problems can still arise.

By being aware of some of the warning signs you may be able to fend off a backup before it becomes a real problem. Some of those signs include:

  • Sewage on the surface of your drain field;
  • The distinctive odor over the field or around your tank;
  • Sinks or toilets are slow to drain (be sure not to ignore this one);
  • Your basement fills with backed up sewage

An Easy First Step
Before calling in an expert for your backup, you can start looking at some of the obvious causes. For example, if one fixture or all the fixtures in one part of the house are slow, there may be a clog in a individual or main-branch pipe; however, if all of the drains are slow, then the problem is likely in the system.

Where’s the Cause
The tank may be full, or the outlet tee may be blocked, especially if you have a dirty effluent filter. If the level of sewage is above the inlet pipe, the tank won’t be able to receive sewage from the house. On the other hand, if the ground over your drain field is wet and smells of sewage, the problem could be in the drain field itself, but you will need to find out exactly where the problem is before taking the time and expense of digging up the entire area.

Inspect the Lawn
Walk through your drain field to determine if something may have damaged the drain pipes. They are usually only about 12 to 18 inches below the surface and if someone drove over the field, the soil may be compacted reducing absorption or the underground pipes may be crushed. Also, look for trees whose roots may have intruded on the system. You should never plant anything over your drain field except grass as the roots from trees and shrubs can get into the drain pipes and clog them.

Since the system should be water tight from the house to the drainfield, a backup in the drainfield will almost always cause sewage to rise to the surface, then cause the tank to flood, and finally then cause pipes in the house to be sluggish.
While looking for drain field problems, observe any areas where the grass seems to be growing greener and fuller. This could be a sign that the septic backup is caused by a broken drain field pipe or clogged soil. However, if the drain field must be dug up and repaired and you’re not a licensed contractor, then you’ll certainly want to call in a professional.

Get the Tank Pumped
By simply pumping the tank, the pumper should be able to give you valuable hints about the source of your problem.  Once the tank is pumped, they will be able to see the inlet/outlet tees or baffles, the effluent filter, cracks in the tank, etc. If one of the tees is broken or the effluent filter is dirty and blocking the system, they’ll be able to tell almost immediately. They’ll also should be able to tell if there’s a crack in the tank or the risers are improperly sealed causing the tank to flood with rainwater.

Septic Backup

Don’t Ignore the Problem
Regardless of the cause and potential cost of repairing a septic system backup, it’s usually not something that will go away by itself. Simply, inexpensive solutions could work, especially if the problem is caught early; however, ignoring the problem will only make it worse and more costly.


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