More info. needed. Approximate dimensions of pond? Does it have a running fountain or waterfall? Always on? Can you see and feel this liner over the cement. Is it heavy (not easy to tear with your hands). This is in a completely enclosed room or building? Where is this garden hose coming from (just curious). Are you saying it takes 8 minutes to fill every day? Then how much water depth was left before refilling? Would it just keep going down if not refilled and how do you know?

Can you just let it drain and see where it stops emptying? That would give you a clue about where to look for the tear. Then it can be easily patched - clean the rubber for good adhesion. It might look kinda ugly for a while sitting there partly empty, but at least you'd save some $$$$ not having to replace a liner.

Good to put leftover scraps of liner - OR SOMETHING - under heavy rocks to keep them from wearing through.

Thank you all so much for your questions.

To answer chas045's questions: The dimensions are difficult to gauge since it's a semi-circle in shape, but it's approximately 15 feet x 5 feet at the furthest edges. The fountain / waterfall is always running. The liner is very thick and strong, yet extremely difficult to tear by hand. The room is enclosed in so far as it is completely indoors, but it's at the center of a very large lobby with very high ceilings. Sorry for the "garden hose" detail, it is not completely accurate (I was getting tired and had to get some other work done!) the pond has a water refill spout that is the approximate diameter of a garden hose and refills at the typical velocity of a garden hose turned on full blast. It does indeed take ~8 minutes to fill everyday, which is a significant increase from refilling it ~5 minutes every 2-3 days. There is ~4 inches of water depth lost everyday at this point.

To answer a question posed by both of you: The reason I do not know if the water would not keep draining if I let the water level drop to a certain point, is that there are several Koi fish in the pond (something I spaced mentioning in the original post). BUT, since the moving of several stones in the "remodeling" of the pond, the water depth is not even refilled as high as it was before. I might be able to let it run down lower and lower to see if it stops leaking at a certain point without compromising the fish's environment. Like you said kashka_kat, it may look ugly, so I'd have to clear this decision with management. In this business, it's all about selling the image! I'll ask them and see what they think.

The only changing factors I can figure from before and after the remodeling is that since there are less large stones in the pond itself, there is an increase in the volume of water in the pond. The waterfall portion is also spread out more to where the water covers a bigger area than before. Previously, it would shoot out somewhat quickly over a 2-3 foot area, where now it trickles down over 4-5 feet and at a slower rate due to the dispersion.

The thing that truly alarmed me to a leak is that I can not configure a variable that has changed other than the water is leaving the pond at a faster and faster rate overtime.

Thank you guys so much for your help so far! This is a good to have your opinions and excellent questions.

OK, I'm almost ready to get alarmed with you big time. Even your original water loss was well above expectations, particularly since this pond is in a controlled environment. Even an eighth of an inch per day is probably a leak or syphon or oversplash. But lets check out the fountain or waterfall plumbing before we panic. I gather that there is a wider than before waterfall that comes from a pump that is recirculating water. Is this pump in the pond, or outside it somewhere. If it is outside, then perhaps you have missed a nice leak going down a drain somewhere?? Otherwise lets panic, start looking for a job before the health department condemns the nursing home.

Actually, how about this theory. This is an industrial building and it has floor drains in many rooms for cleaning purposes. One of these drains was below the impending pond and someone thought 'if this thing leaks, it will just go down the drain'; and they intentionally built the pond on top of it.