Ladies, check your meters if you can. We had a ridiculous bill too this month, 5 times as high. I checked our meter and the actual reading compared to the 'reading' on the DEWA bill was out by a massive amount of units. Take a pic of your reading and send it to DEWA and demand that someone comes around to do a new reading. Makes me so angry...
I'm not sure whether this is true or not, but our relocation consultant told us that it was usual to leave the water heaters on and it made no difference to the bills. Ours are about 300 dhs in winter rising to over 1000 last month and I guess it's the AC that makes a difference (large 4 bed villa). We don't have the AC on much at the moment though...perhaps a few hours in teh evening