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Frequently Asked Questions
Backwater Valve (i.e. Flapper Valve)
Can a backwater valve be installed without a sump pump?
It is not recommended. If the water level in the sewer rises to a level
more than about 5 inches above the top of your basement floor, excessive pressure
may be exerted on your basement floor and walls. This could cause structural
damage. If the water level in the sewer remains below the five-inch level,
the weight of a four-inch thick concrete floor alone should counteract the
extra water pressure.
Is there a backwater valve that you recommend?
The plumber who installs the valve needs to be familiar with the valve,
its installation, and its maintenance. There are a number of plumbers who are
familiar with the flapper valve. It's the simplest and normally functions well
but it isn't perfect. The fact that the flapper valve may be considered the
current state-of-the-art in many places may provide some comfort. I don't know
of any plumbers who have successfully used other types of check or backwater
valves that may be available. Sewage has debris in it and, as a result, can
foul almost any valve.
The flapper valve provides a good measure of protection from sewer backup
but it is not fool-proof. Debris can become lodged under the flapper to keep
it open and allow water to enter the basement. Also a sand-like material can
collect under the flapper.
The flapper valve for our sewer line plugs up from time to time.
It is a rubber type flapper that closes if the city sewer tries to back
up into the house. The blockage is caused by things from our home that
are hanging
up on that flapper. The flapper just doesn't seem flexible enough to
let everything pass. I've replaced the flapper a few times but it doesn't
seem to do any good.
Do you have any suggestions?
The flapper valve is used commonly in the southeast Michigan area and may even
be considered state-of-the-art around here. It's fairly good but it may require
some attention, as you know.
There is no easy answer. However, I will offer some comments.
Just to make sure that we are talking about the same valve, the sewer flapper
or check valve used in southeast Michigan is similar to the check valve (CV04)
sold by Agri-Drain (1-800-232-4742 or www.agridrain.com). I'm not sure if that
is the same valve that you have.
A sewage ejector pump could be installed as a positive way of discharging sewage
from your home into the sewer.
It doesn't solve your maintenance problem, but a manual shut-off valve could
be installed as a backup to the flapper valve. However, you need to be home to
close it. There are two types ot shut-off valves. A gate valve with a valve box
and stem could be installed outside in your yard. The gate valve should be epoxy
coated and have a resilient seat. It may be expensive. Agri-Drain (see above)
sells a less expensive slide gate valve (VV04) that could be installed next to
the flapper valve under the basement floor.
J.R. Smith (334) 272-7396 for literature or www.jrsmith.com) sells a valve that
closes automatically. The gate rises from the bottom and appears to be less subject
to plugging from debris than other valves. However, a plumber in your area would
need to be familiar with it to install it and service it. I have no experience
with it.
Is there an alternate to the flapper valve?
You can install a manual gate valve to act as a backup to the flapper
valve. However, you need to be at home to close it.
One alternate automatic backwater valve is the Flood-Gate as manufactured
by J. R. Smith Manufacturing. It is more complicated than the flapper valve.
As a result, the local plumbers in your area would need to have used the valve
successfully and be prepared to service it. The Flood-Gate operates on air
pressure that slides a gate into the closed position. An interesting feature
of the valve is that the gate slides up into the valve from the bottom, thereby
reducing the chance of the valve becoming obstructed with debris and sand-like
material that may collect on the bottom.
If the backwater valve isn’t perfect and I have to be at
home to close the shut-off valve, I don’t feel very secure. Isn’t
there some better way to protect my basement from flooding due to sewer
backup and give me more peace of mind?
I will offer some comments to those who have sump pumps. You
may want to ask yourself if you really need the plumbing facilities in
the basement? If you were to eliminate the plumbing facilities and sanitary
floor drain(s) in the basement, there would be no way for the water to
enter the basement. If the sewer backed up, the water would rise up in
the sewer pipe to the level of the flooding but could not enter the basement.
The water would stay within the pipe.
One additional thought for those who have sump pumps. Water seeks its own level.
Consider what would happen if you eliminated or plugged the sanitary floor drains
in the basement and left the toilet and washbasin in place. Water could not enter
the basement until the flood level reached the top of the toilet. That's about
14.5 inches high. You would want to check if there is any history of the floodwaters
in the basement getting any higher than that.
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