Add salt to lakes, kill every living thing in and around the lake, deal with an enormous amount of rotting bio matter, and probably poison drinking water for an entire ecosystem.
Add it to pools, deal with salt deposits everywhere that ruin all the pool equipment, and make the water so saline that you can’t dump it anywhere.
It is way easier not drown in the ocean (unless there are waves). In saltwater you can mostly stay still and keep you face out of the water; in pool water it requires a lot more effort (both physical to keep yourself up and mental to control your breathing) and I say this as someone with more fat than the average person)
- salt in high concentrations ist deadly to every lively being.
We, and all living cells or even viruses, need water as solvent for our chem-biological processes. When there are some changes in water/salt ratio - the chemical process stop working.
But that's not the problem with your idea.
The real problem, the drawing would stop, but the people will drink themselves to literally death, as thirst comes up.. or, may be they will turn conservated like pork. Or even dry out like dry mummies
And all the effects salt has on our environment and us. One big point is that non-saltwater organics will die at even low concentration of salt in f.e. in soil, while saltwater organics will die too when salt concentrations level "dead sea" will be spilled into canalization system/rivers wherever.
Of course it's not deadly to swim in salt water. But the salt water is deadly by itself.
Seriously, that's a good question which needs a dumb answer.