Vault toilets work like old-fashioned out houses. They use no water. They are basically a seat placed over a hole. The waste collecting vault is located just below the hole. These vaults are installed just below ground level. They are constructed of reinforced concrete. Vaults typically hold up to one-thousand gallons of human waste. This is typically around ten-thousand uses or more before the vault will need to be emptied. The vault is sloped so that waste will drain down and is lined typically with plastic that is cast directly into the side vault walls.

There are many manufacturers of vault toilets and this type of toilet can be seen in many smaller parks and other recreational areas. Many have vent pipes that are located at the back of the restroom building. These pipes, heated by the sun, provide air flow that keeps the restroom free from odors. New designs have been implemented into vault toilets and can provide the restroom with specific features such as cast concrete walls that look like stone and even gable windows to provide extra lighting.

Many people feel that a vault toilet is simply the updated version of the old outhouse. Although they work around the same principal, vault toilets today are much more sanitary and provide an excellent choice for those areas that have little or no access to running water. They can provide restroom facilities in areas that have no city water or sewage connection. They are very easy to clean and maintain and can be very cost efficient given the lack of water use as well as the price for having them installed.