Septic tank pumping is the process of emptying a septic tank. In this process, sludge or solid waste that has accumulated after it failed to decompose in the first chamber is removed. This sludge should be removed frequently or else the anaerobic digestion system of the septic tank may malfunction leading to hefty repair and maintenance expenses.

Many homes have a septic tank but the owners give little to no attention until when it’s full and a bad smell fills the compound. To fully dive into this topic “septic tank pumping” let’s, first of all, know what a septic tank is…

What is a septic tank?

A septic tank helps to manage your home wastewater and solid waste. A modern septic tank is designed to incorporate two chambers with each having an access opening and a cover for inspection and for the septic tank pumping. The two chambers should be completely watertight and separated by a dividing wall. The two chambers are joined by an opening located about midway between the floor and the roof slab of the tank. The first chamber is constructed to include a hanging wall a few feet from the inlet. This acts as a barrier stopping the incoming waste from passing through the midway opening into the other chamber.

How a septic tank works

The septic tank has two inspection chambers;

• An inlet inspection chamber at one end of the septic tank, and
• An outlet inspection chamber at the other end of the septic tank.

These inspection chambers are useful in observing the flow of wastewater into and out of the septic tank system. The outlet inspection chamber also acts as an inlet chamber of the soak pit.

The wastewater enters through the inlet chamber into the septic tanks’ first chamber. The solid waste then settles at the bottom of this first chamber where they are anaerobically digested, reducing its volume and creating the sludge layer. The impurities lighter than water float on the surface of the first chamber creating the scum layer.

When is septic tank pumping necessary?

When the first chamber begins to fill up, the liquid waste begins to flow through the dividing wall into the second chamber of the septic tank. Here, further settlement of any impurities takes place.

When the second chamber is almost full of liquid waste, the excess liquid will drain through the outlet into the septic drain field or to the soak pit. This liquid is generally in a clear condition state due to the settlement that took place at the second chamber.

For the excess water to drain into the drain field, a Percolation Test must be done before installation or construction of the septic tank. However, this depends on the locality of the area. This tests the porosity of the soil to allow the seepage of the excess liquid coming out of the septic tank to take place. The excess water, although slightly clear, still has some impurities which are then trapped and eliminated in the soil.

Some septic tank outlet pipes have an exit filter to retain the sludge or particles from escaping into the drain field with the wastewater. This may seem like an effective means of reducing the clogging of the drained soil, but in the long run, the second chamber will be full of the retained sludge and impurities necessitating the septic tank pumping.

HOW TO INTERPRET BUILDING DRAWINGS PROFESSIONALLY.

How to tell if a septic tank pumping is ready

Many factors affect the frequency of the septic tank pumping as explained below. However, as a general rule of thumb, it is good to ask the builder to calculate the capacity of the septic tank and give you a rough estimate of when the septic tank will be full. When you know this, you can inspect the first and the second chambers, through the access openings, some months to the septic tank pumping expected date.

In the first chamber, check the depth of the sludge by inserting a rod or pole all the way to the bottom of the tank. When the sludge depth is more than a third of the septic tanks’ depth, pumping should be done promptly before any accumulation of the sludge or septage overflows into the second chamber.

You can also inspect the outlet inspection chamber by checking for any sludge or excess impurities overflowing into the soak pit or the drain field.

Note: the excess liquid from the second chamber flowing into the soak pit should be generally clear, thus, any sludge flowing into the soak pit should be quick to spot.

Other signs that it’s time for septic tank pumping:

• The lawn is suddenly growing with lush, green grass.
• Trouble flushing your toilet.
• Overflowing water in the septic tank area creates a sudden pool.
• Water drains very slowly.
• Your home compound smells like sewage.
• Sewage backup in your drains.

Why does septic tank pumping take place?

The term septic refers to the anaerobic bacteria environment created in the first chamber of the tank. This bacterium is the one that decomposes the solid waste that settles in the first chamber through anaerobic digestion. Since in most cases the rate of the accumulation of the sludge is faster than the decomposition rate, the septic tank has to be emptied periodically.

This fast accumulation is caused by the slow and largely ineffective decomposition facilitated by the low temperatures surrounding the septic tank. This means that the anaerobic bacteria need higher temperatures to effectively decompose the organic material in the wastewater, thus reducing the biological oxygen demand of the wastewater.

The septic tank is “full” in two cases”

1. When the solid waste doesn’t decompose and the accumulated sludge overflows through the outlet into the soak pit or the drain field.
2. When the anaerobically treated wastewater leaves the second chamber into the soak pit, it leaves behind the heavy impurities that settle at the bottom of the second chamber, and also the lighter impurities that settle at the top of the second chamber. Thus, the second chamber fills from the bottom up with heavy impurities and from the top down due to the lighter impurities. When there’s no longer room to hold the heavy and lighter impurities or particles, the particles begin to escape through the outlet and may clog the soil in the drain field or the soak pit. Hence, septic tank pumping needs to be done.

In both scenarios, when no pumping is done, expensive repairs may occur as the overflow sludge can clog the outlet of the septic tank or also decrease the porosity of the drain field soil.

How often should septic tank pumping take place?

The frequency of septic tank pumping depends on the following factors;

1. The capacity of the septic tank and the volume of the wastewater in the tank.
2. The anaerobic digestion takes place efficiently in areas with higher temperatures. Low temperatures mean the high accumulation of sludge necessitating septic tank pumping frequently.
3. The requirements of the local authorities.

To reduce the septic tank pumping frequency;

• Minimize the slowly biodegradable solids such as fats from utensils, toilet paper, etc since they take a long time to biodegrade leading to the fast accumulation of the sludge.
• Avoid introducing non-biodegradable solids such as cigarette filters, plastics, condoms, etc. These types of solids will never decompose and will quickly fill up the chamber necessitating the need for a septic tank pumping.

To avoid a malfunction of the septic tank system, septic tank pumping;

• should be done once every two to three years, or
• You can inspect the first chamber once every year by inserting a long rod or pole into the bottom of the tank. When you withdraw the pole, you will see the depth of the sludge and if the sludge is more than a third of the tank depth, pumping should be done promptly.

How is septic tank pumping done?

The septic tank pumping is done using a vacuum truck. These are hired at a cost that depends on the locality. The process involves breaking up the scum layer and mixing the sludge layer with the liquid portion of the tank. This is done by pumping the wastewater from the second chamber into the first chamber with the solid semi-decomposed waste.

The septic tank pumping is then done through the two main access manholes located at each chamber.

When pumping out the septic tank you should avoid;

• Using any additives to reduce the sludge volume may harm the anaerobic digestion system,
• Completely emptying the septic tank. It is recommended to leave some settled solids to encourage the anaerobic digestion process to continue, and
• As a precaution, you should never enter a septic tank for any reason since it contains harmful gasses that can kill.

Septic tank pumping cost

The septic tank pumping costs between $20 to $60 depending on the following factors:

• Your home distance to the vacuum truck company.
• The size of the septic tank.
• The condition of the septic tank and the need for any repairs.
• The time of pumping includes higher costs for emergency pumping done outside normal work hours.
• Your home geographical location.

Finally,

It is important for you as a homeowner to know when the septic tank pumping has to be done so as to avoid any hefty repairs and maintenance costs. Although the septic tank pumping will be done by a professional company, knowing this information beforehand will ensure you supervise the works to be done according to recommendations. For additional resources check the “septic tank on Encyclopedia”.