My water bill isnt much more than that... If in fact the water bill has gone up that much, I would be more inclined to start checking for "running" toilets, leaky faucets etc...
Oh yea.. just to add, be careful how you approach the topic because even if shes not telling the truth, shes still your mom! Even it was untrue, if you make her mad she could put her foot down and say fine get rid of them all. Remember, you catch more flies with honey
