Basement Watchdog Big Combo review

A complete primary-plus-backup system in one box, with four float switches and two check valves. Also a battery you have to buy, a Wi-Fi module you have to buy, and two different sets of published flow figures.

The Basement Watchdog Big Combo is worth buying in one specific situation: your primary pump is old or dead, your pit is at least twelve inches across, and you want redundancy without having to work out float heights and check valve placement yourself. In that case it is the most complete package on the market and the installation is as close to foolproof as a two-pump system gets. If your current pump is healthy, buy a standalone backup instead and keep the pump.

This review covers the system sold as the Big Combo, which Basement Watchdog also sells as the Big Combo Connect (model CITS-50, Wi-Fi capable with a separate module) and which appears at some retailers as the Big Combination, model BW4000. They are closely related packages and their listings quote different flow figures, which is the single most confusing thing about shopping for this product. We cover that below rather than pretending the numbers agree.

Quick picks

#	Product	Best for	Score	Price
1	Basement Watchdog Big ComboThe most complete primary-and-backup package you can buy in one box, with the float heights and the check valves already worked out — provided your pit is wide enough and you budget for the battery.	Replacing a whole sump system at once	8.4★★★★	Check price on Amazon → #ad we earn a commission · Amazon shows the current price
2	Zoeller AquaNot 508 battery backup systemA self-testing 12 V backup that bolts onto the pit you already have, so you are not throwing away a healthy primary pump to buy redundancy.	Keeping a primary pump that still works	8.6★★★★	Check price on Amazon → #ad we earn a commission · Amazon shows the current price
3	Wayne ESP25N battery backup systemA 12 V backup that publishes its flow at four separate lifts including the unflattering one, and moves more water at ten feet than either system above.	The most backup water at a basement lift	8.5★★★★	Check price on Amazon → #ad we earn a commission · Amazon shows the current price

Scores are ours and editorial, not lab measurements — see how we pick. Tap a row for the full write-up.

What is actually in the box

• A 1/2 HP cast-iron primary pump, published at 4,400 GPH at zero lift.
• A 12 V DC backup pump, published at 2,500 to 2,600 GPH at zero lift depending on the listing.
• A primary controller and a backup controller, the latter Wi-Fi capable on the Connect version with a separate module.
• Two dual float switches — one pair for each pump, so four switches in total.
• Two check valves and a 1-1/2 in rubber union, which is the correct discharge arrangement for two pumps sharing one pipe.
• A battery charger and a battery box. Not the battery.

The published figures, and why they disagree

A ten percent spread between two national retailers describing the same hardware is not a rounding error, and it is worth understanding what it probably means: these are related but not identical packages, and retailer specification sheets in this category are copied between listings far more often than they are checked. Size your system on 3,200 GPH at ten feet for the primary and 1,730 for the backup. If the real figures are the higher pair, you have headroom. If you size on the higher pair and they are not, you do not.

What it is genuinely good at

Four float switches is the headline feature and it deserves to be. In a sump system the motor is rarely what fails; the switch is. A float that fouls against the pit wall, sticks with silt or simply wears out after a hundred thousand cycles is the most common way a working pump fails to run. This system puts two switches on each pump, which turns the single most likely failure into an inconvenience rather than a flood.

The weekly self-exercise cycle is the second. A backup pump that sits idle for eleven months and then fails on the one night it is needed is the default outcome for backup systems people install and forget. A controller that runs the pump periodically, watches the battery and complains when something is wrong converts that from a hidden failure into a noisy one. That is worth more than a few hundred gallons per hour.

And the pre-matched float heights genuinely remove the hardest part of a do-it-yourself backup install. If you have ever stood in a basement trying to decide how many inches above the primary's switch-on point the backup float should sit, you know why that matters. For the full comparison against building your own, see the best battery backup for an existing sump pump.

Where it falls short

1. The battery is a separate, significant purchase. This is standard across the category, but it means the shelf price understates what you will spend by a long way.
2. "Wi-Fi capable" is not Wi-Fi. On the Connect version, remote alerts need the separate CONNECT module. Read the listing carefully before assuming your phone will tell you anything.
3. Two different published flow curves. Covered above. It is not a reason to avoid the system, but it is a reason to size conservatively.
4. No warranty term on the listings we could reach. Most competing systems state two to three years. The absence is conspicuous.
5. Single-manufacturer risk. Both pumps, both controllers and all four switches come from one company. There is a real argument for mixing manufacturers so that one design fault cannot take out your primary and your backup together.
6. Pit size. Twelve inches is the stated minimum and that is tight for two pumps and four floats. Measure before ordering — see what size sump pit.

Who should buy it, and who should not