Pray for rain, Honolulu.

If conditions continue to trend drier going into the hotter summer months, water customers from the Aiea-Halawa area to Hawaii Kai could face mandatory water restrictions and the potential for periods of low water pressure and water outages due to the problems linked to the Red Hill crisis.

“I pray for rain every day,” Ernie Lau, manager of the Honolulu Board of Water Supply, said in an interview. “But we’re still on a drying trend.”

Despite recent moisture, Oahu continues to endure some form of drought islandwide, according to the U.S. Drought Monitor, and it would not be surprising if conditions worsened in the coming months.

While extended drought has led to mandatory water restrictions on rare occasions in the past, Honolulu is dealing with a different kind of situation with the Red Hill water crisis.

The discovery of fuel in the Navy’s water system prompted the Board of Water Supply in December to shut down three of its own wells for fear of the city’s water supply falling victim to the same contamination.

One of the wells is the Halawa shaft, the agency’s largest source of water on Oahu. The source normally provides 20% of potable water to more than 400,000 residents from metropolitan Honolulu all the way east to Hawaii Kai, including Waikiki. The two other wells provide 50% of the water to a smaller system serving 20,000 customers in the Aiea and Halawa areas.

With the Halawa shaft offline, the system’s other wells are pressed into service working overtime. But the extra pumping led to a decision to reduce production at a key well at the BWS Beretania Street station.

The action was necessary, officials said, because the extra pumping was bringing up too much salt into the fresh water, a phenomenon that compromises water quality and threatens to undermine the long-term viability of the source.

On March 10, the Board of Water Supply formally called on all Oahu water users to voluntarily reduce consumption by 10%.

If the problem worsens this summer, the board could impose mandatory restrictions on water use and perhaps place a moratorium on new construction projects in the affected areas.

How long could this go on?

Lau said the crisis is likely to last two years and maybe longer while the Navy investigates the extent of the contamination.

What we do know, he said, is that the groundwater below the Red Hill tanks and nearby areas are contaminated with fuel. What we don’t know is how the groundwater is moving. Officials suspect the contaminated water is working its way across the Halawa Valley toward the city’s wells, which is why the facilities were shuttered.

“We will keep them closed indefinitely — until we can be absolutely sure that when we turn them on, we won’t inadvertently pump fuel-contaminated water from the underground aquifer into these water systems. It would be catastrophic if that happened,” Lau said.

If the investigation confirms the city wells are indeed threatened, the potential for water shortages could go on for multiple summers and multiple years. There may even be some areas that experience lower water pressure or periods of no water during times of critical water shortages.

Lau said the board is not waiting for the results of the Navy’s investigation. He said the plan is to identify new replacement well sites now and proceed with the development process that ordinarily takes seven to 10 years.

“We don’t want to waste those few years (during the Navy’s investigation),” he said.

In the meantime, the board will have to consider mandatory water restrictions if drought continues and water shortages worsen.

Before that happens, however, a formal proposal will be brought to the board, and a public hearing would be held.

Lau said the agency will likely target outside water uses as irrigation usually dominates usage.

One proposal might limit irrigating lawns to certain days, perhaps depending on whether an address ends in an odd or even number. Lawn watering might also be restricted to certain hours, like before 9 a.m. and after 6 p.m. to avoid periods of higher evaporation.

Restrictions might also limit the filling of pools or require turning off water fountains or other decorative water features. BWS has already turned off its water fountain in front of its Beretania Street headquarters.

At first, the mandated restrictions will be left up to the customer to take the responsibility and do the right thing.

But if that doesn’t work, the agency can monitor usage through the water meter and take action.

“If it gets really bad, the board could create a water allocation to every customer, based on past usage, and reduce allocations by a certain percentage,” Lau said.

In addition, the board can raise the price of water for those who abuse the rules or go over their limit. Or there could be a penalty for excessive usage.

“There are a lot of options,” he said. “If someone is being totally abusive and not doing their part, we can put a restrictor in the water meter that will reduce the flow rate, resulting in lower pressure.”

Whatever the board decides, the penalties would get progressively severe only as needed, Lau said.

In the beginning, if a BWS employee observes a violation in the field, he or she might stop to offer a friendly reminder about the rule.

“We hope that people understand that we have to work together,” Lau said.

The board has already reached out to state and city government agencies to ensure they are taking measures to conserve water. The hotels and the visitor industry have also been contacted to ensure they are on board for conservation.

Additionally, 600 letters describing the need to conserve water have been sent to top water users in each of the affected water systems.

“We just want to reassure everybody that we don’t expect the average citizen to bear the burden all themselves. That would be really unfair. It’s everybody’s issue. It’s everybody’s concern. It’s everybody’s challenge,” said Kathleen Elliott-Pahinui, the agency’s public information officer.

Lau encouraged everyone, not just residents in the affected areas, to strive for that 10% voluntary reduction in water use.

He noted that most single-­family residential customers use an average of about 20 gallons per day. That amounts to only four of those 5 gallon buckets you can buy at hardware stores.

“Doing a full load of laundry — and not a half a load — would save you 20 gallons right there,” Elliott-Pahinui said.

And instead of taking a 10-minute shower, do a five-minute shower. In many homes, that alone is enough to take care of the daily 10%, he said.

Lau said preparing for the upcoming hurricane season by storing extra water (1 gallon of water per person, per day for at least 14 days) might take care of two potential emergencies — a hurricane water outage and one caused by the Red Hill situation.

“We’d like to ask everyone to conserve, because if drought is inevitable, restrictions may be necessary islandwide,” he said.