Here's my long story. I have been in this house for 31 years,
the only owner. The house sewer lines dump into a main which
goes to a lift pump, which is like a giant ejector pump, which
pumps the sewage from many houses to the treatment plant about
1/2 mile away. On heavy rains, the lift pumps can't handle the
load. The pumps have diversity AC power from several
substations, so it rarely looses AC power. I have had my floor
drain plugged for almost all 31 years. However, the last big
rain dumped 17" over a 24 hour period, much of it during a 5
hour period ... before the sun came out. I had a check valve in
the laundry tub, however, check valve don't work real well for
slowly rising water, so the tub filled up to the top. I
siphoned it to the sump ... once there was a big pressure
difference between the 2 sides, the check valve slammed tight
and no more water came into the tub. Some water did leak where
the plastic house drains connect to the iron pipe in the floor.
Anyway, I kinda stopped a major disaster by being there.

The point is, I talked to the local municipality and they
analyzed the situation and had a Eveready SafeHouse system
installed (http://www.evereadyfloodcontrol.com/ in the Chicago
area). They have done this in a handful of 'trouble houses'
around town. The installation cost about $5000 3 years ago,
which I didn't have to pay (except for my normal taxes). It is
in my front lawn and has a float activated valve to close off
the house from the city sewer when the water starts rising. It
also has a ejector pump to allow water from the house drains to
be pumped into the now backing up sewer system. The whole thing
is installed in an underground vault that you can actually climb
down into. It seams to work, however, we haven't had any of the
big 100 year rains which seems to come about every 5 or 7 years.
One side effect of this system is that my regular sump pump
almost never runs now. The neighbors, who all have similar
problems to me, are pumping out large amounts of water with
their sump pumps, however, my sump is still bone dry and we have
had lots of rain in the last 2 weeks. I don't know if the pump
in the SafeHouse system is pumping out the water, or if the big
manhole in the front yard is just somehow diverting the water
.... maybe to the neighbor's house?

Artfd wrote:
I am posting this since the information available on the internet is
somewhat sketchy, and various contractors & plumbers I have consulted
have not given me specific information even though I requested it.
Northeast Ohio had record rainfall this 3rd week of July 2003. My
town had 6 inches of rain fall in 45 minutes that day. Most of the
homes in my neighborhood are more than 30 years old. Most of the town
is on a hill top, shaped like somewhat like a mesa, and many homes had
sewage backup through their floor drains and basement toilets.
Homeowners who had spent $5-10,000 to have their basements
waterproofed were surprised to learn their waterproofing guarantees
specifically excluded coverage for these events.
My basement has not been waterproofed, and it occasionally leaks
when 2 inches or more of rain fall in an hour, but I just live with
it. I don't have a sump pump. That night I had 5 inches of slightly
contaminated water, which erupted through my floor drain, flooding the
basement floor within 20 minutes. Within 90 minutes the bulk of the
water had drained out the way it came in. Some of my neighbors had
wet vacs stored in their basements. The wet vacs tipped over when
their basements flooded, ruining the vacs at the time when they were
most needed. I had my wet vac upstairs in my garage, fortunately,
and I used to to get rid of most of the remaining water that night.
An area of carpeting in the basement was ruined, and I pulled it up
and got rid of it over the next few days. The event happened while
the local stores were still open, and naturally there was a run on
sump pumps, and within an hour all local stores were sold out. I
consulted my plumber the next day and the only advice he gave me was
to plug my floor drain temporarily (which could only be done if I were
at home, since the floor drain is also the only way my footer drains
can exist the property). He did mention the possibility of
retrofitting a backup valve in my sewer line between my floor drain
and the street connection, but it would be expensive to retrofit due
mostly to the excavation necessary. He didn't inform me of other
possible measures, neither did the city sewage department or the
building inspection department. It is mandatory in our city that
businesses have sewage backup prevention built into their drains, but
not residential construction. A great many of our older homes have
their downspouts and gray water draining directly into their sewer
connections, which of course promotes sewer overflows during heavy
rains.
I did a Google search on "sewer backup prevention" and I got 9,200
hits describing various means of prevention. The first page had a
dead link from the Illinois DNR, but I was able to access the page in
Google's cache, and learned some basics that my contractors did not
tell me. The main problem was that measures recommended were usually
too vague to help most homeowners.
The simplest measure is the drain plug, widely available in
hardware stores. In emergencies a mop jammed in the drain might work,
although one of my neighbors who tried this found his basement toilet
erupting with a 3 foot high geyser of sewage instead. This could
have also happened if he a drain plug, which would make me consider
that a basement toilet is a no-no unless some more definite means of
backflow prevention