A backwater valve is a
backflow prevention device
A backflow prevention device is used to protect potable water supplies from contamination or pollution due to backflow.
In water distribution systems, water is normally maintained at a significant pressure to enable water to flow from the tap, s ...
used to prevent outbound water through a dwelling's drain pipes from re-entering -- "
back flowing"—into a home. The valve contains a flap that allows water to exit the home, but closes to prevent the back flow into the home.
Backwater valves commonly activate when a city's sewer lines are unable to handle a large amount of falling precipitation; this puts homes that are tied into the storm lines at risk of having water back flow into them.
There is a big difference between backwater valves and backflow preventers:
* A backwater valve prevents raw
sewage
Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system. Sewage consists of wastewater discharged from reside ...
from backing up into your home through your
toilet
A toilet is a piece of sanitary hardware that collects human urine and feces, and sometimes toilet paper, usually for disposal. Flush toilets use water, while dry or non-flush toilets do not. They can be designed for a sitting position popu ...
s,
shower
A shower is a place in which a person bathes under a spray of typically warm or hot water. Indoors, there is a drain in the floor. Most showers have temperature, spray pressure and adjustable showerhead nozzle. The simplest showers have a ...
s, etc.
* A
backflow preventer
A backflow prevention device is used to protect potable water supplies from contamination or pollution due to backflow.
In water distribution systems, water is normally maintained at a significant pressure to enable water to flow from the tap, ...
deals with protecting a potable water source from being contaminated by a reverse flow of foul water (ex: isolating your toilet's flush cistern and water supply from the toilet bowl water itself).
See also
*
Check valve
A check valve, non-return valve, reflux valve, retention valve, foot valve, or one-way valve is a valve that normally allows fluid ( liquid or gas) to flow through it in only one direction.
Check valves are two-port valves, meaning they have ...
References
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Plumbing valves
Water
Sanitation
Backflow