As the name suggests, Flush-Vaults™ are flush restrooms built over vaults that contain the sewage.
Vault restrooms are typically installed in areas not served by sewer or septic systems. They utilize a subterranean containment chamber below the building (the vault) to hold waste. Most vault toilets constructed in recent years are built to meet the “Sweet Smelling Toilet” standards promoted by the U.S. Forest Service. When built to these standards, odor is reduced, but may still be present when there is limited air flow around the building or in locations where there is very heavy use. Vault toilets are equipped with a toilet seat mounted on a fiberglass riser located over a hole in the floor. The contents of the sewage vault are easily seen when looking down the toilet riser. This causes many visitors to think of vault toilets as revolting and unsanitary and many visitors totally avoid vault toilets for these reasons.
From the floor down, a Flush-Vault™ is the same as a vault toilet. However, with Flush-Vaults™ the toilet riser is replaced with a flush toilet. If a public water supply is not available, a water storage tank is installed in a mechanical room. A hand wash sink is typically installed, something you won’t find in a vault toilet. The result is a vault toilet system that the public recognizes as a flush restroom without the unpleasant odors or visuals.
This method is made practical by using toilets designed to use very little water (typically about one half-gallon per flush). The capacities of the water tanks vary from 2,500 to 5,000 uses. The vault capacities vary from 4,000 to over 20,000 uses. Like vault toilets, Flush-Vault™ restrooms are built over coated and sealed precast concrete vaults that contain the sewage until it can be pumped and hauled away.
Since these restrooms are not limited by the “Sweet Smelling Toilet” design principles that normal vault restrooms must adhere to, a cabin can be equipped with more than one commode. A Flush-Vault™ can have any number of toilet stalls with no odor problems.
Where potable water is not available, flush water is processed through a high-efficiency filter and can come from irrigation, harvested rainwater, or from another non-potable water source.
Another problem with Vault toilets is that waste disposal can be a pain. Have you ever seen a sign in a vault restroom that says “never throw garbage down the hole because it’s extremely difficult and expensive to remove”? Vault risers have large holes to throw things into. But a flush toilet cannot pass anything larger than 2” in diameter. This eliminates the garbage problem. The use of water for flushing also means the sewage is only 10% solid, which also makes the job of pumping the vault easier.
Flush-Vaults™ can go anywhere there is vehicle access, just like a Vault toilet can. Currently,Green Flush Technologies is the only American company offering Flush-Vaults™. They are being offered at prices comparable to vault toilets.