Sizing for a Sump Pump — Keeping the Basement Dry in an Outage
Last verified: September 2026
The cruel part of a sump pump is the timing: the storm that knocks out your power is usually the one filling your basement. Here's how to size a backup that keeps it running — and where a battery backup fits. Rather talk it through? My number is (330) 200-8042.
Sizing for a Sump Pump, at a Glance
A sump pump is a motor, so it needs a brief starting jolt on top of its steady running watts — and the cruel timing is that the same storm that knocks out your power is usually the one filling the sump. This guide explains how to size your backup to start the pump, not just run it, where battery-backup and water-powered pumps fit, and why you should test the whole plan before storm season. There's a printable page-by-page version up top.
Common Questions
1 Why does a sump pump need its own backup plan?
Because the storm that causes the outage is usually the one filling your sump. Unlike a fridge, the pump often needs to run hardest at the very moment the outlet goes dead, so a tested backup is what stands between you and a wet basement.
2 How do I size for a sump pump?
Read its nameplate for running watts and a starting figure, then make sure your backup can deliver the surge to start it — with headroom — while the fridge and lights are already running. It's a motor, so plan for the brief jolt, not just the steady draw.
3 Is a battery-backup sump pump worth it?
For most basements that flood, yes. It's a separate little system that kicks in automatically with no generator needed and can buy you hours. It pairs well with a generator for longer outages.
4 Will a water-powered backup pump work for me?
Only on city water. It uses municipal water pressure to pump the pit, so it needs no electricity — but on a private well there's no pressure once the power's out, so it won't work.
5 Do I add the sump's surge to all my other surges?
No — you add your steady running total plus the single biggest surge. The sump competes for that one surge slot with the fridge or well pump; you never stack every motor's surge together.
6 Can I put a battery backup in the basement safely?
Yes — a battery makes no exhaust, so it's safe indoors right by the pit. A fuel-burning generator, by contrast, always runs outdoors, well away from the house, with a cord run in.
Would You Rather I Just Help?
A sump pump is small until the day it's the most important machine in the house. I'll help you read its nameplate, size a backup that can start it, add a battery-backup layer, and test the whole thing before storm season — with nothing to sell you. $99 flat for a visit, 30-day come-back-free.
Would you rather I just do this for you?
No shame in it — plenty of folks would rather hand it off, and that's what I'm here for. I'll come to your home, set it up right, and make sure it's working before I leave. Flat $99 per visit — no jargon, no upsell, and every visit is 30-day come-back-free.
Not a hardware job? I can often fix it remotely for $49 — a secure screen-share, up to 2 hours, that you watch the whole time and can end whenever (included free for $39/mo Support Plan members, and it counts toward the $99 if it turns out I need to come out).