The number of Honolulu Board of Water Supply customers getting bills showing they were undercharged or overcharged has gone down to just over 1 percent, officials said.

But exactly how many of the water agency’s roughly 166,000 customers got an "estimated" bill at some point this year remains unclear.

Ernest Lau, the board’s water manager and chief engineer, said he and his staff have been too busy trying to deal with the billing conflicts caused by the estimated bills to even ask its information technology staff to run the numbers on how widespread the problem has been.

"We’re just tracking total number of bills each month," Lau said. "Our whole thing was just to get the numbers down."

Asked by the Honolulu Star-Advertiser how many customers had gotten at least one estimated bill since the beginning of the year, the board on Friday released numbers showing a staggering 78 percent of customers getting such a bill. Of those, 62 percent were undercharged and 16 percent were overcharged, board officials said.

But on Saturday, less than 24 hours later, Lau said he was not confident those numbers were correct and asked for more time to provide more accurate figures.

Other numbers given to the Star-Advertiser by the agency on Friday showed the number of customers getting estimated bills each month from January to September. March saw the highest number of estimated bills, with 94,643 customers, about 59 percent of all Oahu water customers, getting estimated bills. Of those, 84,282 were undercharged and 10,371 were overcharged.

City Councilwoman Kymberly Pine has introduced legislation that would ask voters to consider an amendment to the City Charter that would bar the water agency from charging customers retroactively. Pine said she has never received as many complaints on any issue as she has from constituents about the water board’s estimated bills.

"I believe it is fundamentally wrong for a government entity or a private entity to back-bill customers six months back and say six months later, ‘Oh, by the way, you owe us this much more because we made a mistake on your bill,’" Pine said.

Ewa Beach resident Robyn Camacho opened her family’s July water bill to find she had been under-billed by $1,400.

"They said we were billed an estimated amount (from January to June) when in actuality, readings were taken so here’s the difference," she said. The family typically pays about $130 a month for its combined water and sewer bill, Camacho said.

Camacho said her husband was able to locate a leak in the system, and the Camachos argued that because the board did not give an accurate reading, the family should not be penalized for the entire spike when the actual readings were found. A compromise was reached and the Camachos ended up getting a credit for half, or $700, of the "under-billed" amount.

"I understand why they had to back-bill," Robyn Camacho said. "We were mainly frustrated at the way it was delivered to us."

She said that the $1,400 bill did not include any information explaining the situation or offer payment options beyond the regular monthly payment period. "If they had said they would give us some time to pay it back, I wouldn’t have been so upset."

Lau, who has apologized repeatedly for the estimated bills and the related problems they’ve caused, said that in more recent months, letters have been mailed out to customers explaining that they have payment options.

Punchbowl area resident Tim Dayton ended up paying $600 more based on seven months of underpayments. Dayton said he was mailed seven months of bills that he could not interpret. When he got through to an employee, he said, the woman was polite and told him readings were made but not used in favor of estimated numbers.

"This made no sense at all," he said.

A week later, he got another bill with an even bigger balance, he said.

Dayton, a business executive himself, said, "If this was a private business competing with others, they would be losing a lot of business. But they’re a public monopoly."

Water officials said a "perfect storm" of issues that cropped up at the beginning of the year are to blame for part of the large increase in estimated bills.

First, the batteries on thousands of automated meter reading devices — installed in roughly 155,000 homes in the early 2000s — died around the same time, giving zero readings. Water officials said previous administrations deferred maintenance to cut costs, including the replacing of batteries that are supposed to last only seven or eight years.

Typically, a zero reading would result in a visit from a meter reader who could manually do two other things to try to obtain a reading. But in January, the agency switched to a monthly billing system after issuing bimonthly bills for decades. A number of additional readers were hired in anticipation of the change, but not enough to handle the large increase in zero readings that now needed to be dealt with in one month rather than two months as had been the norm before January, said Henderson Nuuhiwa, program administrator for the board’s Information Technology Division.

"We didn’t have enough staffing in place," Nuuhiwa said. With new readers in place, 98 percent of meters were read in September, up from 85 percent in January, he said.

The agency, because it is focused on addressing the billing issues of customers, still has not analyzed what else could have led to the large increase in estimated bills, Nuuhiwa said.

Typically, the only other time an estimated bill is generated is when a recorded meter measurement is flagged because it is significantly higher or lower than other recent bills. The "high-low threshold" mechanism in the city’s newly installed Customer Care and Billing System Program is used to flag meters that may be recording a leak (resulting in a higher reading) or a malfunction (causing a lower, or no reading). If a manual review does not take place before the billing cycle is over, a bill is generated based on an estimated read, Nuuhiwa said.

How much of a deviation from the normal reading is needed before it is flagged is based on algorithms determined by the Oracle billing system installed in January, he said.

Staffing was again an issue because not enough pre-audit section clerks were in place, water officials said. Additional clerks have since been hired.

BECAUSE ESTIMATED water bills are considered an accepted industry practice (and the agency in typical months issues about 3-4 percent of its bills based on estimated readings), the board did not detect until May that an abnormally large number of customers were getting estimated bills, water officials said.

Of 235,253 estimated bills issued from January through September, 186,198 (79 percent) were underestimated while 49,055 (21 percent) were overestimated, board officials said. The amount that had to be given back totaled about $19.8 million while the amount that had to be collected was about $23.7 million, leaving a net amount owed to the board of about $3.9 million, water officials said.

Nuuhiwa said Lau has asked staff to look into the possibility of changing the formulas that determine when a high-low threshold is reached and an estimated bill is generated.

"The data on which the estimation process relies may be inadequate," he said. Board officials chose to go with the stock formulas initially, rather than customized versions, because of the difficulty and costs involved when Oracle issues system patches or fixes.

"On balance, estimation is never really a major issue as long as it doesn’t continue over a long period of time," Nuuhiwa said. "The challenges occur when estimation occurs month after month after month. There’s a compounding effect at that point. And that’s why you get back to the staffing issue."

Lau said he is vehemently opposed to Pine’s Charter amendment proposal prohibiting the water board from charging later for earlier underpayments.

"We want to bill people for water they actually use through water meter readings because that’s fair to our customers," Lau said. "But the reality is there is always a need to estimate bills at some point."

Estimated bills are used by all utilities, Lau said, and even in its best months through the years, 3 to 5 percent of water meters show up with errors or no readings due to a variety of reasons.

Further, Lau said, if the board were denied the ability to charge customers for previous underestimated bills, it would also be barred from crediting customers for overestimated bills.

The main point, he said, is that the number of customers getting estimated bills is now back down. It was less than 2 percent in September.

"We’ve worked really hard to get that number down," he said.

Both Mayor Kirk Caldwell and Water Board Chairman Duane Miyashiro contend Pine’s plan would go too far.

"I don’t support any form of legislation that would tie the hands of the Board of Water Supply," Caldwell said. "It’s an entity that should be run as independently as possible."

Caldwell said the high numbers of estimated bills earlier this year were unacceptable. However, he said, "I think the worst is over now … corrections were made and they’re getting back to their previous levels now."

Miyashiro echoed Caldwell’s comments. "We do not think it is appropriate for the Council to second-guess the collective judgment of the board," he said in a statement. "The board certainly appreciates these issues being brought to our attention and we will continue to monitor the situation to ensure that our policies are fair for all of our customers."

Pine’s resolution was given preliminary approval by the Council earlier this month and forwarded to the Executive Matters and Legal Affairs Committee, which is headed by Councilman Ron Menor.

Menor said Saturday that he has not yet decided whether Pine’s proposal will be aired in his committee when it meets at the end of the month.

A separate resolution introduced by Menor and passed earlier this month by the Council calls on city Auditor Edwin Young to conduct a management and performance audit of the water board.

Menor said he is inclined to let Young finish his audit before any Charter amendment proposals are sent to voters. The deadline for Charter amendments to be placed on the fall 2014 ballot is not until next summer.

A third resolution involving the water board was introduced by Councilman Ikaika Anderson earlier this year. That plan called for asking voters to approve a Charter amendment giving Council members the final say over the water board’s budget and land use decisions. That resolution has been shelved by Council members, some of whom said they want to see what Young’s audit will recommend.

Lau said he supports an audit and welcomes any suggestions Young’s staff may give.