I have two water basins in our front yard and I have to top the water up in both every 2-3 days. The first photo seems to lose water the quickest. Too fast to be evaporation so I'm guessing it is leaching out as I see no obvious signs of holes in them with water coming out. Guess they are clay same as the large clay bowls you see to collect water. We keep tad pole type fish in them as the wife says they eat mosquitoes. They were both topped off with water yesterday but already can see the lower levels, especially the 1st photo.

Any ideas as to how to seal them? Specific sealant material and possible source of them in Chiang Mai. Something that won't kill the water lilies and fish.

Thanks.

Suspect water proofing paint would work but know that they make a water proof white cement that works well as used it on portions of outside wall to stop water entry.

Believe or not - it might just be evaporation. We have similar and one gets slightly more sun than the other and, yeah - that's what happens. If you don't see obvious leaks, then what else could it be?

Believe or not - it might just be evaporation. We have similar and one gets slightly more sun than the other and, yeah - that's what happens. If you don't see obvious leaks, then what else could it be?

what else could it be?

Does the OP have any dogs, I have seen dogs drink from these.

I have also seen birds bathe in them, the birds flapping their wings about could be causing the loss of water.

Try the bucket test to check if it's evaporation.

Mark a plastic bucket about 1/2" from the top, fill to the line (with water), place it by the more 'leaky' pond into which you have placed a level marker (bamboo stake with a line on it stuck in the lilly soil). Jack the bucket up on bricks so the level is level with the pond for a more accurate result.

Leave alone for 24 hours.

Check how much the two levels have dropped, if the pond has dropped much more then the bucket, you have a leak.

No dogs and don't see birds settling in and I'm out front several times a day. We have an aquarium on the front porch, but not directly in the sun, and it's weeks before I have to top it off. Also have another basin but different material, more stone like, and it is directly in the sun as these and maybe every few weeks I have to top it off. Two-three days is just too fast. Filled them yesterday and they are down nearly 1 to 1.5 cm already.

Considering cutting a black garbage bag to size and cover the bottom but not very attractive. I can't see any leaks via holes but wondering about the water leaching into the material and slowly coming out.

So, are those new installs? If the material is soaking up the water, then it will saturate at some point and then leak. Maybe compared to your other stuff, there is reflective wall or like that?

So, are those new installs? If the material is soaking up the water, then it will saturate at some point and then leak. Maybe compared to your other stuff, there is reflective wall or like that?

At least one year old. I will take a closer look tomorrow to see if the outside walls are damp. It is on a pedestal so will examine the bottom of the pedestal if it is wet. It is a lot worse then it was a few months ago when it was cooler.

If the pots are unglazed they will seep over their whole area, you won't even see it.

The big pots (ongs?) the MiL uses for drinking water seep slightly, evaporation keeps the contents cool.