Help me get my dog to drink water!

We adopted a dog about 6 weeks ago - 4 year old, male, neutered, GSD mix, 75lbs. Overall he has been settling in well but we have discovered that he does not drink enough water. Like - so little water! especially for a dog his size. I would consider just chalking it up to that's who he is, but we did a full work up at the vet when we adopted him and the vet noted that he is dehydrated (concentrated urine), had a very small amount of crystals in his urine, and had a barely elevated SDMA marker. Since we don't have much history on him, the vet recommended that we retest in 3 months and try to get him to drink more water in the meantime.

He seems to be peeing normally (not excessive, urgent, painful, or having accidents inside etc). I don't think he would have a UTI because, unfortunately, we also discovered he is HW positive so we are in the beginning stages of that treatment, which is 30 days of 2x daily doxycycline.

The only water he reliably wants to drink is our swimming pool, or dingy gross water from an old fountain in the yard that's full of rotting leaves, which we have been discouraging...but I'm beginning to wonder if I should just let him drink it because it's better than nothing!

These are the things we have tried - would love any other suggestions!

• Cleaning his bowl every day - no change

• Different bowl materials - no change

• Multiple bowls in different locations (including outside)- ignores them all

• Dog water fountain - had 3 sips out of it when I first got it, has ignored it since

• Broth in water - mostly ignores

• Canned Tuna or Sardine liquid in water- Will occasionally drink, largely ignores

• Filtered water vs tap water - no change

• Ice cubes on the floor - likes them, but are they bad for his teeth? Also such a small volume of water.

• Ice cubes in water bowl - ignores

• Putting a SMALL amount pool water with mostly regular water in his bowl (getting desparate lol) - no change

• Putting treats in water - ignores

• Canned wet food on top of kibbles - he likes this, but it's not nearly enough water for this to be the only solution

• Making "kibble soup" with water/kibbles - this has worked until today, he would eat all the kibbles and drink all the water. But this morning he picked out all the food and left most of the water :/

The next step to try is soaking /mashing his kibbles, but realistically I don't see how this is going to get the 8 cups of water per day he's supposed to be drinking into him, without it being kibble soup as mentioned above, which he seems to have outsmarted. Any other magic bullets or ideas?