Drain a Dehumidifier Into a Sump Pump
Written by the Dehumidifier for Basement editorial team and reviewed for source accuracy. — last updated July 2026. Editorial policy · Report an error
Quick answer
Run the dehumidifier's drain hose over the lip of the sump pit (or through a drilled port in the lid) so condensate falls into the pit by gravity. The sump pump ejects it outside along with groundwater. Keep the hose end above the water line, not submerged.
Can you drain a dehumidifier into a sump pump pit?
Yes, and it's one of the most common continuous-drain setups in basements, since almost every finished basement already has a sump pit. The dehumidifier's own drain relies on gravity to reach the pit; the sump pump then handles pushing that water (plus any groundwater) out of the house. You are not plumbing the dehumidifier directly to the pump — you're just letting gravity-fed condensate join the water the pump already handles.
Does the sump pit need a sealed lid for this?
A sealed or gasketed lid is recommended by radon-mitigation and moisture-control standards, since an open pit is itself a humidity source that adds to the basement's RH — working against the EPA's 30-50% target. Drill a 3/4-inch hole in the lid for the drain hose to pass through, or buy a pre-drilled sump lid ($15-$30) instead of removing the lid entirely.
| Item | Spec/Note |
|---|---|
| Hose size | 5/8 in or 3/4 in GHT, matching drain port |
| Lid hole size | 3/4 in-1 in, sized to hose OD |
| Hose end position | 1-2 in above the pump's high water mark, never submerged |
| Check valve | Not required for gravity drain; only needed on a condensate pump discharge line |
| Sump pump capacity used | Negligible — a dehumidifier removes at most 2-5 gallons/day |
Why keep the hose end above the water, not submerged?
A submerged hose end can siphon sump water backward into the dehumidifier if the pump cycles and pressure changes in the pit, or it can let sewer gas travel back up the hose in pits tied to a drain-tile system. Keeping the end 1-2 inches above the highest water level the pump allows before cycling avoids both problems.
Tools needed
- Garden hose or vinyl tubing
- 3/4 in drill bit (if drilling the lid)
- Drill
- Zip ties
- 1Confirm the pit is lower than the dehumidifier's drain portGravity flow requires the pit opening to sit below the port height.
- 2Drill or find an entry point in the sump lidUse a pre-drilled lid or drill a 3/4-inch hole near the edge.
- 3Route the hose from the dehumidifier to the pitKeep a continuous downward slope, secure with zip ties along the way.
- 4Position the hose end above the water lineZip-tie or clip it to the inside wall of the pit, 1-2 inches above the pump's normal high-water mark.
- 5Test the pump cycleRun the dehumidifier and confirm the sump pump activates normally and no water splashes back up the hose.
What if the sump pump is uphill from the dehumidifier?
If the dehumidifier sits in a spot where its drain port is actually lower than the sump pit rim, gravity won't work and you need a condensate pump to lift the water into the pit, typically over 5-10 feet of vertical lift through 1/4-inch tubing.
Will this overload my sump pump?
No. A residential dehumidifier removes roughly 2-5 gallons of water a day even on a high setting; a typical 1/3 HP sump pump moves 25-30 gallons per minute. The added volume is a rounding error compared to storm or groundwater flow.
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Frequently asked questions
Do I need a check valve on the dehumidifier drain line into a sump?+
No, check valves are for pressurized discharge lines like a condensate pump's output. A gravity drop into an open pit doesn't need one.
Can I drain into a sump pit with no pump, just a gravel bed?+
Yes, if the pit drains passively into gravel or a drain-tile system, that still works as long as the hose end stays clear of standing water.
Will drainng into the sump pit cause odor?+
Occasionally, if the pit is tied to a sewer connection. A sealed lid with a small drilled hole for the hose minimizes gas escaping into the basement.
What if my sump pit doesn't have a lid?+
Add one — an open pit adds humidity to the room, working against what the dehumidifier is trying to remove.
Is this legal or against code?+
Draining a small volume of condensate into an existing sump system is standard practice and doesn't require a permit in most jurisdictions, but check local plumbing code if the sump ties into municipal storm drains.
Keep reading
Sources and methodology
Guidance on this page is drawn from federal agencies and industry standards bodies rather than our own laboratory testing. We do not test appliances in a laboratory and we do not publish product measurements we did not obtain from the manufacturer or a government listing.
- U.S. Environmental Protection Agency — Mold Course & moisture control guidance (keep indoor relative humidity 30–50%)Used for: Target indoor relative humidity range and mold-growth conditions. Last verified 2026-07-29.
- U.S. Department of Energy — Energy Conservation Standards and Test Procedure for DehumidifiersUsed for: Why capacity ratings changed: the current federal test procedure and its rating conditions. Last verified 2026-07-29.
- ENERGY STAR (EPA) — ENERGY STAR Certified Dehumidifiers product finderUsed for: Certification status, Integrated Energy Factor (IEF) values, and sizing guidance for dehumidifiers. Last verified 2026-07-29.
- Association of Home Appliance Manufacturers (AHAM) — Dehumidifier certification program and sizing guidanceUsed for: Capacity-by-condition sizing ranges and certified capacity verification. Last verified 2026-07-29.
- U.S. Energy Information Administration — Electric Power Monthly — average retail price of electricity, residential sectorUsed for: Default electricity rate used in operating-cost estimates. Last verified 2026-07-29.
Written by the Dehumidifier for Basement editorial team and reviewed for source accuracy. Last updated July 2026. Found an error? Report it through our corrections policy.