Plain tap water can kill minnows, shad and other bait fish, because almost every municipal water supply is treated with chlorine or chloramine to make it safe for people to drink -- and both are toxic to fish. Minnesota's DNR tells anglers to refill bait containers with bottled water or de-chlorinated tap water, and defines de-chlorinated water as tap water that has either sat out overnight to let the chlorine escape, or been treated with an aquarium water conditioner. Which fix actually works depends on which chemical your water utility uses.
Why plain tap water is dangerous for bait
Fish don't tolerate chlorine the way people do. University aquaculture extension guidance on dechlorinating water for aquatic animals says even the slightest trace of chlorine can prove fatal, and describes chloramine -- chlorine combined with ammonia, which many utilities add as a longer-lasting disinfectant -- as very toxic to fish and other aquatic life as well. Either one sitting in a bait tank works against everything else you're doing to keep bait alive.
Chlorine and chloramine aren't the same problem
The two need different fixes. That same extension guidance notes that chlorine will gas off with vigorous aeration over about 24 hours, testing down to zero. Chloramine is more stable and does not de-gas as easily, so running an air stone overnight can still leave measurable chlorine and ammonia behind. That's the gap in the DNR's advice: letting tap water sit out overnight reliably clears chlorine, but if your utility uses chloramine instead, standing water alone may not finish the job.
How to make tap water safe
Check which disinfectant your water system uses before deciding how to treat it; most utilities list it in their annual water-quality report. For straight chlorine, aerating the water for roughly 24 hours and retesting before trusting it works, per that extension guidance. For chloramine, or if you don't want to wait a day, a chemical neutralizer breaks the chlorine and ammonia apart. The extension guide's own classroom dosing -- a 4-pound jar of neutralizer treating about 65,000 gallons at 1 part per million of chlorine -- shows how little it actually takes to treat a full bait tank. A conditioner made for bait tanks and livewells does the same job without requiring you to measure out chemistry yourself, and some also calm ammonia and support the slime coat bait fish lose when they're handled.
Simplest of all: fill the tank with water from the lake you're fishing before you catch your bait, so it's already free of chlorine and already close to the temperature your bait is coming from.
Common mistakes
- Assuming a day of standing water handles any tap water -- it reliably clears chlorine, but not chloramine.
- Topping off a low tank with straight tap water mid-trip, undoing whatever treatment the rest of the water already got.
- Never checking which disinfectant your utility uses, so you're guessing at which fix you actually need.
- Swapping in a large volume of new water at once -- a big, sudden change stresses bait even when the new water is clean.
Shop the gear
- Snowball's Bait Tonic AquaZapp -- a water conditioner that keeps live bait lively, for treating tap water before it goes in the tank.
Frequently asked questions
Can I just let tap water sit out overnight?
It depends on your water. Minnesota's DNR counts an overnight stand as one way to get de-chlorinated water, and that works for plain chlorine. Chloramine, which many utilities use instead, doesn't degas the same way, so standing water may not clear it.
How do I know if my water has chlorine or chloramine?
Check your water utility's annual water-quality report, which lists the disinfectant it uses. That determines which dechlorination method will actually work.
Does a water conditioner remove both chlorine and chloramine?
A conditioner made for bait tanks or aquariums is built to neutralize both, which is why it works even on chloramine-treated water where standing alone won't.
Is lake water safer than tap water for a bait tank?
Yes, as long as it's filled before you catch your bait and is close to the temperature your bait is already in. It skips the chlorine question entirely since it was never treated.
Will treating chlorine also fix a foaming tank?
No -- a chlorine/ammonia conditioner and a foam treatment solve different problems. Treat each one for what it actually is rather than expecting one product to do both.