Backup Sump Pump
Installation
in Maryland

Most Zoeller battery backup units run 5–7 hours of continuous pumping on a full charge under moderate inflow, or 2,000–3,000 gallons depending on cycle frequency. During a storm where the power is out and inflow is heavy, plan for 4–5 hours of effective operation. Combinator systems (primary + backup in one basin) extend this.

Test your battery annually — a battery that hasn't been tested in 18+ months may not hold charge when you need it. Maryland storm events routinely knock out power for 6–12 hours in suburban counties. If your basin has high inflow, ask your OBW inspector about a dual-battery system that effectively doubles your runtime.

The honest caveat: no battery backup is an indefinite solution for an extended outage with sustained inflow. If your basement has serious hydrostatic pressure, the backup buys you time — it doesn't replace a primary pump that's working.

Yes — and here's the honest reason: primary pumps fail exactly when they're under the most stress. Heavy storms create the conditions that kill pumps: power surges before the outage, sustained motor run time, float switches that jam from debris, and motors that burn out from running continuously. The backup exists for the scenario where your primary fails at the worst possible moment.

Every Maryland basement that floods with a primary pump present flooded because the primary failed — not because it was absent. Power outages during Maryland storms are common. BGE reports tens of thousands of customers lose power during significant storm events in the Baltimore metro area. Your pump is useless if it has no power.

Think of the backup as flood insurance for your sump system specifically. A flooded basement in Maryland typically runs $8,000–$25,000 in remediation and contents loss. A backup pump system costs a fraction of that — and it transfers with the house under OBW's Lifetime Transferable Guarantee.

Water-powered backup systems use municipal water pressure — not electricity — to run a venturi ejector that pulls water out of the sump basin. They require no battery and have no moving parts to fail. The catch: they consume roughly 1 gallon of city water to remove 2 gallons of sump water. During a sustained storm event, that's meaningful municipal water usage.

More practically: water-powered backups are not permitted in all Maryland municipalities. Some jurisdictions have banned or restricted them because of the water consumption ratio. Before specifying a water-powered unit, OBW confirms local code compliance.

Battery systems are more universally applicable, more reliable in terms of known runtime, and don't depend on municipal water pressure staying up during a storm. For most Maryland homeowners, battery backup is the right answer. Water-powered units make sense in specific situations — well water (no municipal connection), households with very modest inflow, or as a tertiary layer behind a battery system.

In most cases, yes. If the basin is large enough to accommodate both pumps and the float arms don't interfere with each other, a backup can be drop-in installed. The float arm for the backup is set 2–3 inches above the primary float — that way the backup only activates when the primary fails to keep up.

Older clay or concrete basins — common in pre-1980 Maryland homes — sometimes need to be replaced with a larger plastic basin before a backup can be properly installed. OBW assesses this during the inspection. A basin upgrade is typically a straightforward half-day job if needed.

One situation where a drop-in backup doesn't work well: very small-diameter basins (under 18 inches) where two pump bodies and float arms can't coexist without interfering. In those cases we recommend basin replacement as part of the backup install.

Sealed lead-acid batteries in sump backup systems typically last 3–5 years under normal conditions. Factors that shorten battery life: heat (basements that get very warm in summer), frequent discharge cycles (your primary fails often, meaning the backup runs regularly), and neglect (a battery that sits on a trickle charger but is never tested degrades faster than one that's exercised annually).

Lithium-based backup systems last considerably longer — 7–10 years — but come at a higher upfront cost. OBW installs the system type that matches your expected use and budget.

We don't install systems without battery health indicators. You shouldn't be guessing about battery condition before a storm. The indicator tells you when replacement is approaching — not when you're already in trouble. OBW's annual maintenance plan includes a battery discharge test as part of the service visit.