Landlords and billing companies argue it's environmentally responsible to estimate how much to charge unmetered apartment residents for their water because the little-known practice could save drought-stricken Maryland up to 7.2 billion gallons of water a year if it's expanded.
But that assertion - made in a filing to a Howard County commission that is considering whether to regulate unmetered water billing in the county - appears to be unsubstantiated, some experts say.
The question of whether unmetered apartments should be billed has stirred debate across the nation. Tenants who live in a complex that uses unmetered billing, often known as a Ratio Utility Bill System or a RUBS, do not have their water and sewer costs included in the rent but instead pay a share of the complex's total water bill.
The study used by the unmetered-billing advocates to project water savings lacks statistical integrity and should not be used to set policy, water conservationists say.
They contend that the study, titled "Submetering, RUBS and Water Conservation," has too small a sample size, does not fully examine whether residents use less water after they start paying for it and fails to fully analyze key elements about rental cost and plumbing infrastructure.
The study is "statistically worthless. If it is being used for anything other than anecdotal evidence, I would strongly, strongly object," said Dan Strub, a water conservation specialist with Austin, Texas.
In the third of four scheduled public hearings, the Howard County commission will hear testimony on the billing issue at 7 tonight in the second-floor conference room of Columbia Gateway Building, at 6751 Columbia Gateway Drive.
Generally, the landlord will pay a percentage of the total bill, while the rest is divided among residents according to a formula that depends upon variables such as the number of rooms, people or square feet in their apartment. Depending on the formula, a single person in a two-bedroom apartment could pay as much in water and sewer charges as a family of four that lives in a similar unit.
Some communities have banned the practice and jurisdictions such as Montgomery County and Memphis, Tenn., are considering regulating it.
At least two dozen Howard apartment complexes make their residents pay for water and sewer and residents have complained that RUBS bills force them to pay far more for their water and sewer than residents of single-family homes.
Some apartment dwellers pay more than $40 a month for their services, almost four times the amount the average family of four living in a house should pay, according to county officials.
"Submetering, RUBS and Water Conservation" examined data on 32 properties in Texas, Florida and California. The properties either did not charge their tenants for their water and sewer, used submeters, which keep track of the water and sewer each apartment uses, or used a RUBS.
The study then compared the groups against each other and found that apartments that use submeters use between 18 percent and 39 percent less water than apartments that include it in the rent. RUBS properties used 6 percent to 27 percent less than apartments that include water costs in rent.
Doug Koplow, one of the study's two authors, agrees that the study's sample size is small and that it did not fully statistically analyze variables such as plumbing and the cost of rent, although researchers tried to compare properties that were built about the same time and had roughly the same rents, Koplow said. "We didn't get clean data on [every variable] and we tried to make that clear in the study ... but this is the best study out there that I'm aware of," he said.
But some water experts say plumbing and rent costs must be a part of any reliable study.
Results will be skewed if a structure that has low-flush toilets is compared with an older building that has outdated plumbing and uses much more water, experts say.
Or a high-rent complex, where richer tenants generally care less about the cost of water and use more, could be compared with a low-rent apartment, where dwellers are more cost and water conscious, experts add.
"If you would ask [water billing advocates] today if they were confident in that study, they should say 'no,'" said Eddie Wilcut, a water conservation planner for San Antonio, Texas.
"Those estimates don't stand up. ... I don't know any utility that has used that study for any projection or planning efforts," said Al Dietemann, a senior program analyst with Seattle Public Utilities.
"The study should not be relied on. They neglected too many crucial elements in their research," said Peter Mayer, vice president of Aquacraft Inc., which is conducting a nationwide study of water billing practices sponsored by several water districts and the Environmental Protection Agency.
Water billing advocates acknowledge flaws in "Submetering, RUBS and Water Conservation" but say it is an important tool.
"It is not anecdotal. It's very much a controlled study done by professional statisticians. ... Anyone who would call this anecdotal is not very mathematically skilled," said Bill Griffin, vice president of National Water and Power, a billing agency that operates in Howard County.
Griffin is also a co-chairman in the National Submetering & Utility Allocation Association, a trade group that represents billing companies.
Griffin said he has conducted an analysis of the 17 Howard County properties that use National Water and Power services and that his analysis indicates that each complex saves, on average, 2 million gallons of water a year. County officials and independent researchers have not verified those estimates.
Jim Caffey, the executive vice president of the nearly 230-member Maryland Multi-Housing Association Inc., said that the study was the "most definitive" available and that he has seen its results validated at local apartment complexes that use RUBS or submetering.
"I've heard enough anecdotal evidence about water use dropping that tells me the report is accurate," he said.
But San Antonio water conservation specialist Wilcut has his study, which shows that RUBS do not conserve much water. In a survey of 15 properties in the San Antonio area, Wilcut found that people who lived in RUBS units used 57.6 gallons a day on average while people who lived in units that were not charged for water used 59.2 gallons of water a day.
While Wilcut said that his study is not definitive, "it doesn't seem like there's much savings with RUBS ... especially if they don't retrofit with low-flow toilets," he said.
Other water experts agree with Wilcut.
"If I thought [RUBS] would help save water, I would be in favor of it but I don't think this is about water conservation. ... This is being driven by landlords and billing companies who are trying to make a profit and shift the burden to tenants," said Amy Vickers, an independent engineer and author of the book "Handbook of Water Use and Conservation."