Sump pumps and basement water
Summary: A sump pump lifts groundwater from a basement pit to the outside. In Indianapolis it must discharge to the yard or a storm sewer, never the sanitary sewer. Celtic Rainwater Systems installs basement sumps with interior drains and exterior sumps for downspout lines[2][3].
What does a sump pump do?
A sump pump sits in a pit, or basin, at a low point of a basement floor. Groundwater collected by a perimeter drain flows into the pit, and when the water rises to a set level a float switch turns the pump on and pushes the water out through a discharge pipe[1]. Citizens Energy Group describes their job simply: sump pumps “protect basements from high groundwater on the outside of the walls”[2].
Where can it discharge in Indianapolis?
Citizens says sump pumps “should discharge out of the house and into a yard or have a connection to a storm sewer”. If the sump line connects to the same pipe as toilets, showers and sinks, the clear water is going to the sanitary sewer, which is not allowed[2]. Its warning that “as few as six sump pumps” can fill a sewer serving 200 homes shows why. Discharge onto the yard should be far enough out, and downhill, so the water does not just cycle back into the pit.
What is an exterior sump?
Celtic Rainwater Systems also uses sump pumps outside, as part of downspout drainage: where a yard is too flat for gravity, downspouts run to a basin and a pump lifts the water to a discharge point[3]. That is different from a basement sump, though the equipment is similar.
What should I ask about a sump system?
- Where is the pit, and is it at the low point where water collects?
- Is there a perimeter drain feeding it, or does it only catch water that reaches it on the floor?
- Where does the discharge go, and is it legal under Citizens’ rules?
- Is there a check valve on the discharge line so water does not drain back into the pit?
- What happens if the power fails during a storm? Battery backup and water-powered backup pumps exist for that case.
- Is there a lid on the pit to keep debris, pets and children out and limit moisture?
The company says it will plan basement work to match “your space and align with your budget”[3]. Get the plan in writing, with the pump type and discharge route.
Should I fix the outside first?
Often, yes. A basement that leaks only in heavy rain may be getting roof water dumped next to the wall. Check gutters, downspout discharge and grading before paying for interior drainage. Where the water table is high, an interior drain and sump may still be necessary.
See also
- French drains
- Location and hours
- Downspouts and the sanitary sewer
- Drainage services
- Hiring a gutter contractor
Common questions
Where should my sump pump discharge in Indianapolis?
Outside into the yard, or to a storm sewer. Not into the sanitary sewer, per Citizens Energy Group.
Does Celtic Rainwater Systems install sump pumps?
Yes, for basements and as exterior pumps in downspout drainage systems.
Why does my sump pump run during dry weather?
It can mean a high water table, a discharge that returns to the pit, or a failed check valve. Have it checked.
References
- ^ Sump pump. Wikipedia. Accessed 9 November 2026.
- ^ a b c Our Wastewater Correct Connect Initiative. Citizens Energy Group. Accessed 9 November 2026.
- ^ a b c Drainage (PVC downspout drainlines, French drains, basement drainage and sump pumps). Celtic Rainwater Systems (celticrainwater.com). Accessed 9 November 2026.