QUESTION: How often should a septic tank be pumped?

ANSWER. There are many guidelines about how often a septic tank should be pumped. The absolute answer is to measure the amount of sludge and scum in the tank and pump when it exceeds recommended levels. Remember that the septic tank acts as a separation device separating solids and greases from the water. It takes time for this to happen and generally the tank should be three to four times larger than the daily flow of waste. This gives three to four days for the water to pass through the tank. As the tank fills, this time is reduced and the effectiveness of the tank declines.

Another way of looking at this is to remember that the most expensive part of the septic system is the drainfield. Therefore every effort should be made to protect the drainfield. The only thing in the septic tank that generally has the potential to fail are the baffles. These can be inspected at the time of pumping. Perhaps a better guideline is to pump the septic tank at least every three years so that the baffles can be inspected and the drainfield protected. If there is heavy usage of the system, them more often may be warrented.

The basic guideline is NOT to let the tank fill up so much that it becomes ineffective. Even though some septic tank additives may help improve the efficiency of the septic tank, they should not be used to delay pumping and inspection. No additive can eliminate proper pumping and inspection of this vital component of your system.

QUESTION: What are the baffles?

ANSWER: The baffles on the inlet and outlet side of the septic tank are designed to prevent solids and greases from passing directly through the septic tank to the drainfield. Modern designs also have a gas deflector to prevent the gases released from the biological action from carrying some of the solids out of the tank. These generally are made of concrete or plastic. They may also incorporate a filter to help prevent large pieces of solids from passing to the drainfield.

QUESTION: What is the difference between a seepage pit and a cesspool?

ANSWER: Both of these systems rely on a pit as the water absorption system. In general these will be older systems because in most areas permits cannot be obtained to install pits anymore. A seepage pit has a septic tank in front of it which collects the solids and greases. A cesspool acts as both the septic tank and the soil absorption system. While many cesspools and seepage pits operate for years, they are more prone to failure and are more difficult to restore. Proper maintenance can help extend their lives.

QUESTION: What is the distribution box?

ANSWER: The distribution box performs the function of ensuring that each lateral received the same amount of water. As the box receives water from the septic tank and fills, water is distributed equally to each lateral. The distribution box should be level in order for this to happen, however there are inserts available for the exit pipes which can help regulate their level. These are generally half-moon discs which fit into the pipe and can be rotated to change the level at which water can pass into the lateral.

While many system designs have distribution boxes, there are also many which do not. The lack of a distribution box does not necessarily mean that the system is “defective”.

The distribution box can also function as a window into the drainfield. It should be easily accessed and the water levels inspected several times a year. If it is not easily accessed, then a riser should be put over it to make access easy. If there is no distribution box, then a riser should be placed in the line between the septic tank and drainfield to perform this function.

QUESTION: What is a riser?

ANSWER: It is essential that the septic tank be available for inspection and cleaning. In order to facilitate this, a riser can be placed over the lid and inspection ports. This will allow access with minimal disturbance of the yard and reduce potential time and costs for maintenance. The riser is generally plastic pipe which has a base on the septic tank and in some cases may replace the actual lid on the tank.

The same situation occurs for the distribution box, A riser can make inspection of the water levels in this component of the system easier. It also provides access for any treatment of the soil absorption system.

If there is no distribution box, the a riser can be added to the system by putting a “T” or a “Y” adaptor in the pipe between the septic tank and the soil absorption system to allow for inspection or treatment of this component of the system. It is better if the adaptor allows a six inch piece of pipe to come the surface since this makes it easier to observe the conditions in the drainpipe at the bottom treat the system if necessary.

QUESTION: Why do seepage pits and cesspools fail more often?

ANSWER: Seepage pits and cesspools were generally installed where there was good soil drainage. This was important since they have small soil absorption areas. If there is a relationship between the amount of surface area and the ability to absorb water, then most of the water in pits is absorbed through the bottoms. The side walls account for a small amount of absorption since there is little water pressure available to drive the water into the ground. As you go further from the pit, the water pressure also decreases. Over time, the soil outside the pit will become saturated which also decreases the ability to function as an absorption system. This is one reason why a large amount of water can be pumped from a seepage pit or it can fill quickly after pumping. The water from the surrounding ground is draining back into the pit.

The treatment of a seepage pit or cesspool depends on treatment of the bottom to improve the water absorption ability. Because the bottom is almost always going to be anaerobic, this also increases the possibility of failure.

QUESTION: What if I have a pump in my system to raise the water to a higher level?

ANSWER: A pump in the system can indicate either a pressurized soil absorption system or merely a drainfield that is higher that the septic tank. Both soil absorption systems can fail and will build up anaerobic by-products. Both systems can be treated in the same way as a conventional system. Water should be removed so that the water can get out of the laterals into the ground below. The Septic-Scrub can be added to the pump chamber, water added, and the pump manually operated to transfer the Septic-Scrub to the drainfield. The only thing to note is that not all of the Septic-Scrub is transferred since not all of the water in the pump tank is removed during each pump cycle. Some additional Septic-Scrub may be needed to ensure the full amount is transferred to the drainfield.