Chlorinated tap water is often blamed when seeds fail to crack, although the real effect is usually small. Municipal chlorine levels are low, but some cities use chloramine, which does not evaporate when water sits out overnight. For a pack I ordered at https://budweedseeds.com, I used filtered water for half the seeds and tap water for the rest out of curiosity. Both groups sprouted at similar rates, so I now worry more about water temperature than treatment.