Above Ground Septic Tanks: A Review

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In general, above-ground septic tanks (also called "holding tanks") are wastewater storage tanks which sit above the ground. Small, portable polyethylene tanks are made in 250 and 350 gallon sizes, and these are appropriate in some situations for temporary storage of sewage. Above-ground tanks may also be appropriate in water-front areas where below-ground storage and leaching is prohibited.

The Drawbacks of Sewage Holding Tanks

While holding tanks are occasionally used in seasonal cottages that don't have up-to-date plumbing options, permanent above-ground tanks are rarely used (at least in the United States). They suffer from a number of drawbacks:

• If they are not paired with a leaching field, they need to be emptied regularly: an often unpleasant (and potentially expensive) task.
• If the above-ground tank does work in conjunction with a leaching field, the sewage is typically transported into the tank via a pump (rather than gravity.) This can cause the solids in the sewage to be chopped into smaller pieces, and to escape the tank along with the effluent. As the solids settle out of the effluent, they can block the pipes that lead to the leaching fields.
• Since above-ground tanks are exposed to the elements, they have a tendency to wear out more quickly than their cousins buried under several feet of earth.