I didn't realize the evaporation amount is so high. I have two barrels
one pouring into another, around 40 gallons. From the sun and drops
that splashed out, I have to top about 2 gallons a day.

I plan to replenish water via my drip system for the plants. It will
be tap water but it will drip out to replenish the water. Will it be
OK? I think we have chlorinmine. I only plan to use it during 10-14
day vacations.

What about I place a big tub of water in a seperate container and use a
siphon hose to equalize the water so the evaporation have as much
impact?

Does anyone have ideas for an auto top off system that won't cost too
much?