Thinking about sump-thing

I’ve been thinking for a while … thinking about the sump plumbing. What do I need to connect to the sump, how should I connect it, and where should I connect it?

Sump plumbing should be relatively straightforward. So why did I have to think for a while? Because I also tried to build some future proofing into the system. Plus, I needed a seamless switch from the old repurposed grease trap to the new sump.


There is the water draining into the sump. We had the interior footing drains routed into the old grease trap. Those will now need to drain into the new sump. There also will be exterior footing drains that I need to connect to the pit.

I also have to pump the water out of the sump. That means re-routing the existing sump discharge into the sewer from the grease trap to the new sump pit.

It is typical to pump the sump water into the combined sewer system. But it is not ideal, because Chicago’s combined system barely copes as it is. Adding more water is best avoided and I have little interest in contributing to combined sewer overflow into the Chicago River or Lake Michigan. Plus the water draining from the footing drains into the sump is ground water, a valuable resource that I could use for irrigation.

At one point we will have a underground cistern in the back yard, which should be fed by the roof runoff. But I also could increase the size of the cistern and, in addition to the roof runoff, feed it with the sump water. That should provide me with a nice reliable water supply for irrigation.

To pump the water out of the sump into the future cistern, I need to rough in a discharge connection now. Once I activate that connection, I can cap the discharge into the sewer, or I can keep it, put the pump on a timer, and use it to flush the sewer once a day.

Why would I want to do that? It goes back to the check valve functionality issues we encountered. Our low flow fixtures don’t generate enough waste water volume or velocity to flush solids effectively past the check valve gate. Using the sump water at around 50 gallons per minute (gpm) to flush the system would alleviate that problem.

Last but not least, I need an electrical conduit through which I can route the sump pump power cords to an GFCI outlet on the basement wall.

Related Posts:

Sump-thing pretty heavy

Digging for sump-thing

Terminating the temporary

Grease trap cleaning

Nail biter

Perimeter drain installation

Check Valve and low flow – functionality issues

About Marcus de la fleur

Marcus is a Registered Landscape Architect with a horticultural degree from the School of Horticulture at the Royal Botanic Gardens, Kew, and a Masters in Landscape Architecture from the University of Sheffield, UK. He developed a landscape based sustainable pilot project at 168 Elm Ave. in 2002, and has expanded his skill set to building science. Starting in 2009, Marcus applied the newly acquired expertise to the deep energy retrofit of his 100+ year old home in Chicago.

2 thoughts on “Thinking about sump-thing

  1. If you want to use the same pump for filling the cistern and flushing the sewer do you not need a way to control the flow direction like a set of valves, one open the other one closed?
    Or maybe I just do not understand the brilliance of you setup?

  2. No brilliance in the set up – just a “very rough” sketch, that doesn’t show – but should show – two sump pumps. One for the discharge into the cistern, and the other one on a timer to flush the sewer.

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