They sent me out an estimated bill this quarter which was almost twice what I expected. They then sent me a revised bill a few days later based on an actual reading which was almost 1/2 the estimate.

I'd check your bill - see if it says actual or estimate.

Water usage rates were increased earlier this year.

I was on the phone with them last week for a different issue, but she said they went up 17 percent in the last year.
Water bills generally do go up in summer, (more showers, gardens) but I don't know any rule of thumb percentage.

april thru july H20 was nearly DOUBLE what my my bill was jan thru april.

beyond some family members each taking 2 or even 3 (short) showers per day during the unbearably humid weeks, didn't use that much more...

compared to last year these months, my bill at least one- third more.

has United Water increased the water and sewer charges per CCF(unit of measure?) in the last year? anyone know?