What Is Septic Tank Float, And Should You Be Concerned?

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Owning a home with a septic tank comes with a range of extra considerations and responsibilities. If you're a first-time septic tank owner, then it's crucial to understand how your system functions so that you can keep it properly maintained. As with most aspects of homeownership, septic systems work best when you follow a regular maintenance schedule.

Pumping your tank every few years to clear solid waste and grease is the best way to avoid problems, but there are a few potential snags to keep in mind. Septic tank float is one issue that you may not be aware of if you haven't dealt with these systems in the past.

What Is Septic Tank Float, and What Causes It?

You may think that a large, bulky item like a septic tank would always remain buried belowground, but this isn't necessarily the case. Septic tanks come in a wide range of shapes, sizes, and materials, and some tanks can be more massive than others. For example, fiberglass or plastic tanks may only weigh a few hundred pounds.

Lightweight tanks can often make installation more manageable, but they come with some downsides. When filled, the wastewater in these tanks helps to keep them grounded. Unfortunately, an empty tank can float upwards if the surrounding soil becomes saturated with water, such as after heavy rain. When this happens, it can damage the tank's plumbing or even cause it to drift to the surface.

Note that float is not a concern for concrete tanks, which have enough bulk to remain seated even when the water level rises. Tank installers may also use anchors to ensure that lightweight tanks stay in place.

Should You Worry?

Whether or not you should worry about tank float depends mostly on your system's design, so it's crucial to know as much about your septic tank as possible. Three key issues determine whether septic tank float may be a problem for you:

  1. Is your tank constructed from a lightweight material?
  2. If so, is your tank anchored to the ground?
  3. How high is the water table near your home?

Unanchored, lightweight tanks installed on properties with high water tables will be at the most significant risk for floating.

What Can You Do?

Fortunately, a correctly installed septic tank should not float under normal circumstances. To avoid potential problems, do not pump your tank if you've recently experienced heavy rains or the area around your tank is saturated. Since your tank is only really at risk while empty, this is usually enough to avoid any problems.

When pumping lightweight tanks, it's also a good idea to refill the tank with water immediately. Concrete tanks will naturally fill in a week or less, but speeding up this process will reduce or eliminate float risk in lighter tanks. By working with a septic tank service, you can safely pump your tank while mostly removing the risk of tank float.