I don't buy the PVC and fire issue. So maybe we should insist on using bare wirings to make it less harmful during a fire due to the plastic in the wiring insulator?
Anyway, down the drain if you have muni septic. Check your septic if you have a sept tank, but unless your fish tank is almost as big as your septic tank, there should be no concern... I don't know septic, so you may want someone with a certification there. As for the lawn, it is a bad idea, particularly if your grass got 99.5% of the water from sprinkler and you only turn it on once a week, like around here. If you are putting salt on your driveway to melt the ice on winter, then pour it on it will certainly save you a few dollar in rock salt.
For me, I use it for cooking. Never buy any soy sauce since 1996 when I started the hobby.... :wink: