We got our MLGW bill today and it was up $90 from last month.  I have a few theories as to how it got so high, but I thought I would see if anyone else's skyrocketed.

Mine was more this month but the weather is getting warmer and I like my A/C.

You need to check your last months bill and see where the extra cost was applied.

ALWAYS watch for a big change in your water usage,  that can be a bad sign.

At least 70% of the houses in this area are built on solid concrete slabs laid back in the mid-late 1950's.   A water leak under the slab can go undetected for weeks....

I would suggest you monitor each bill and watch for big changes in usage. 

Our water usage doubled from 4 to 8.  My husband checked the hot water heater and didn't see a leak.  How would you detect a leak elsewhere?  We did have some friends do several loads of laundry, which could have contributed to a good increase in usage too.