Since the water loss bugs aren't fixed, I went back to using a combination of liquid vents and liquid valves to solve my problem, but now those are broken too. If you stop looking at a liquid valve, it'll stop compressing water and the water will slowly but surely get backed up until the whole system just breaks. I kept wondering why I kept coming back and needing to turn off my liquid pumps.
Thermal Upgrade edition
I've experimented a bit more and I understand now. So if you stop watching a water consuming building, it will stop working, but water will continue pumping towards it. As it isn't doing anything with the water anymore, the water will start to stack up. So in my case of having liquid valves that clamped the water pressure to 1000 g/s instead of 10kg/s, the water valve would become pointless as all the 1000g/s water blobs would start to stack ontop of eachother and turn into a 10kg/s blob, completely ruining the purpose of my liquid valve.
Steps to Reproduce
Use a liquid consuming building with water valve constrained inputs, go offscreen somewhere and the building will stop working. A little offscreen doesn't seem to do anything.
Status: Known Issue
We are aware of this issue and have it logged internally but either we do not have a fix ready yet or we are not planning on addressing the issue in the immediate future.