Maybe the crooks were thirsty and drank the pool contents...
...reminds me of Trailer Park Boys - a Canadian comedy - one episode one of the boy decided to bootleg vodka - the RCMP show up to bust one of the boys but they search the trailer and can not find the contraband vodka so they leave. Two of the boys get in a fight because one thinks the other ripped off the missing vodka and during the fight they bust the side of the above ground swimming pool - which was filled with vodka not water...