Honolulu water ratepayers’ response to a doubling of the billing fee is suffering from what could be described as Last Straw Syndrome. Costs are going up on everything, including the water rates. The boost is meant to cover long-overdue maintenance of the city’s water system, and everyone gets that they have to pay up for something like that.

But moving to a monthly billing system means they also are paying the $7.02 billing fee every month instead of every other month, and that’s just the last straw.

The change to monthly billing from the previous two-month cycle was approved about 18 months ago as one of the lesser elements in a broad plan for rate increases. As such, it flew under the radar of most members of the public, which was unfortunate. People hate unpleasant surprises, especially in the wallet.

So the Honolulu Board of Water Supply should do what it can to soften the blow. It should take another look at its schedule for additional increases in the billing fee. Under the current schedule, the $7.02 monthly processing fee will notch up to $7.70 this July, then to $8.44 in July 2014 and to $9.26 in July 2015.

Utility officials say that the decision to go to a monthly system of billing was made in part to ease the budget planning for customers. Those on fixed incomes in particular might have a tough time squirreling away enough for two months of water charges. The cash-flow problem is a bit easier paying on a monthly basis.

But it’s not at all clear that ratepayers would have favored the change had they known the billing fee would be doubling as a result.

Just by itself, the billing fee that once cost about $42 a year will, starting July 2015, be an annual charge of about $111. And that is on top of the added costs they will shell out for water system improvements: approved in 2011 to be a 70 percent increase in rates over five years.

But the question remains: Was the entire increase necessary?

The water board responds that its fee will be comparable or less than other utilities charge, adding that it will cover various expenses. These include repairs and maintenance of the remote meter-reading system, hardware and software required for the monthly billing system and personnel and other overhead costs. For example, planned upgrades include an online bill-payment system, and some revenue is needed to pay the credit-card charges.

So far, however, there’s been no indication of any improvement that’s going to improve efficiency in a way that will benefit the ratepayers. It’s time for the customers to push back by demanding to know how the utility plans to cut costs rather than simply passing them on.

The water board offers various ideas by which customers can reduce their water bills. Most of us have seen these before — taking shorter showers, watering lawns less frequently, nozzling the garden hose and installing water-efficient fixtures. Some of the customers Star-Advertiser writer Alan Yonan Jr. interviewed are coming up with their own solutions, such as rain catchment systems.

Indeed, these approaches can be helpful not only in keeping down water bills but in addressing Oahu’s chronic drought concerns.

However, it’s not only the customer who needs to economize. And Honolulu’s ratepayers deserve to know what steps the water board is taking to control its bottom line, other than tacking on additional charges.