Inspector Pumphead’s Classroom: Graywater vs. Sewage Water

Gray water vs sewage water
Inspector Pumphead is lecturing on wastewater

Welcome to Inspector Pumphead’s Classroom! In this series, I will discuss various aspects of pumps, pumping technology and the pump industry. I’m here to school you on pumps. So pull up a chair, open up your notebook and grab a pen – it’s time for class!

Wastewater

Graywater or effluent is “used” water that does not touch any urine or fecal matter. Most of the water fixtures in your home will produce graywater. Sinks, washing machines, laundry discharge, shower water – all of that is considered graywater. Different pump types are capable of handling graywater and the solids therein; in a general sense, effluent pumps, sump pumps and dewatering pumps are capable of handling graywater. While we always recommend that you purchase a pump matched specifically to your application, there is some crossover. A good example is the Zoeller 53-0001 Mighty Mate which is listed as an effluent pump but can also be used for general dewatering applications.

A good rule of thumb to remember is that effluent pumps are capable of handling up to ¾” solids.  This is good because things such as soap scum, oil, grease, laundry detergent residue and other particulates often accumulate in the wide variety of water fixtures that produce graywater.

Sewage, by contrast is typically only produced in toilets, at least at the residential level. Sewage is defined as any used water which is touched by human waste like urine and fecal matter. Unlike graywater, which is recycled through usable systems, sewage water is exported for treatment. This exported sewage can go to either a septic tank or a city sewer line. 

As would be expected, you need a sewage pump to pump sewage out of your home or building if you do not have a gravity line. Sewage pumps are built to handle and transport 2” diameter waste solids. Grinder pumps are a subcategory of sewage pumps equipped with a cutting system that chops waste solids into a fine slurry for higher head export. Unlike the crossover effect with effluent pumps,sewage and grinder pumps should really only be used for sewage water.

So if you didn’t know before, you now know the difference between graywater and sewage water and what type of pump you need for each. Knowing is half the battle – that’s the promise of Inspector Pumphead’s classroom baby!

Pump Products applications engineers are standing by to help you find the right pump, as well as to provide price quotes, availability and shipping information. Call our toll free number 1-800-429-0800.