If you’ve been keeping up with our special “hump Day, Pump Day” series on sump pumps, you’ll remember that we’ve so far discussed sump pumps and their uses, and we’ve moved on to back-up sump pumps. Last Wednesday I went over one type of back-up sump pump with you, the battery-powered back-up. This week, I’ll explore the second type: water-powered back-up sump pumps. How do these work? Well, the pump utilizes a phenomenon know as the “Venturi Effect”. Essentially, CITY water flows through a nozzle in a pipe extending into the pit. The water flowing through the nozzle increases in velocity, thus decreasing pressure in the pipe. This decreased pressure “sucks” water out of the pit. It combines with the city water and is discharged to the exterior. Two bummers with this system: One- you MUST have CITY water. It will operate with a well pump, but if your electric goes off causing your sump pump to not work, the same power outage will cause your well pump to not work also. So, city water it is. Two- same as with the battery pump, the water powered pump will pump about ½ the volume as the primary pump. Again, this is still better than nothing.
I have seen some Do-It-Yourself videos on how to install a water-powered sump pump, and generally here are two rather important installation cautions that are either glossed over or ignored: first, back flow prevention. This pump is connected to your potable water system. It is also immersed in nasty water in your sump. This is known as a cross connection. It is possible for the nasty water to get into your potable water piping and contaminating it. The back flow preventer is designed to prevent this. However, there are varying degrees of cross connection hazard and, thus, various back flow devises. Back flow devises range from a dual check to a Reduced Pressure Zone back flow. Basically, back flow devises are a whole series of blogs that will bore you to tears. Suffice it to say, a back flow preventer is required on a water powered sump pump. My experience is that local codes require a Reduced Pressure Zone type of back flow. This is an expensive piece of equipment and must be tested by a licensed back flow professional. You don’t want to be cavalier about this-call your local plumbing inspector and make you have the proper back flow device installed-whether your hire a plumber or do it yourself.
Second, most installation videos show the discharge pipe from the water powered pump connecting to the discharge pipe of the primary sump pump. Again, check local codes. Some jurisdictions require the discharge pipe to run to the exterior INDEPENDENTLY of each other. Baltimore County, Maryland requires a reduced pressure zone backflow device AND separate discharge piping. Be attentive to the code requirements… they are there for your health and protection.
I trust by now, you’ve got the basic idea of sump pumps and their various back-up options. What do you have? Do you feel secure in the event of pump failure, a power outage and possible flooding? I hope so! Check back next week for an all new pump-related discussion!