Why does the water in my rain barrel evaporate quickly?

Question

I have some rain barrels in my yard. After a certain amount of tinkering, they collect rain water well. However, I notice that a day or two after the rain, most of the water is gone. I've checked for leaks in the barrels and their hoses without finding any. I also moved the rain barrels out of direct sunlight as much as possible. Is it normal to lose so much water this way? Is it evaporation, or something else?

The barrels are entirely covered, except for a small hole where the water gets in. They are in my back yard, so I doubt that anyone else is using them. And the cats wouldn't be able to get at them for a (several gallon) hearty drink.

Besides the rain barrels, I have some buckets to do rain catching. These do not seem to lose water at the same rate. What gives?

Answer 1

I think the problem is that some leaks are hard to find. If they are covered, it seems impossible for evaporation to be the problem. (I'm assuming that you have 30-50 gallon barrels and they are half full or so after a rain.)

What I would recommend if the barrels are empty right now, and assuming they drain down to be nearly empty:

1. Raise the barrels on blocks if you can do so safely.
2. Fill with just a couple gallons of water from a hose.
3. Put some sheets of newspaper or cardboard (something that will show drips) under the barrel, and see if you can see a leak. Or use a cookie sheet dusted with flour.

It sounds like they don't lose all of the water. If they're only going down to a certain point, it's possible that you have a slow leak on the side of the barrel. To find this sort of leak:

1. Wait until the barrels are full. (Or at least above the water level they reach when they've leaked.)
2. Dry the outside of the barrel thoroughly.
3. Dust the outside of the barrel with flour. Watch for spots that become damp.

When you find the leak, see if you can repair it -- the method will vary depending on the material your barrels are made out of. If you bought them new from a big box store and haven't had them too long, you can probably just return them and get a replacement.