MANILA - Water concessionaire Manila Water committed "two mistakes" that led to the water crisis that has left taps dry in households across Metro Manila, Metropolitan Waterworks and Sewerage System chief regulator Patrick Ty said Friday.

Speaking to reporters, Ty said the water concessionaire's failure to construct a treatment facility on time and its wrong simulation on how to address its supply shortage created a "domino effect."

"Unfortunately, when they announced that there would be a water shortage, people started to panic and people started to hoard water and even areas that were not supposed to be affected started hoarding water. That caused the sudden drop in the reserve," he said.

The concessionaire had to again draw water from the La Mesa reservoir, an emergency source, since its Cardona Water Treatment facility in Rizal has yet to be completed, he said.

"Since the weather did not cooperate, the depletion [of water supply] went faster," he said.

"It led to a domino effect and affected a majority of the system," he said.

The Cardona plant was supposed to be completed last December 2018 but was delayed due to "technical issues," Manila Water Communications Manager Dittie Galang said in an interview on DZMM.

Pipes in areas that were not supposed to be affected by the shortage were shut off to divert water to cities that were drying up, Galang said.

"Dinirekta lang po namin 'yung tubig na nakukuha nila noong mga nakaraang araw sa mga areas na talagang kailangan para magkaroon ng tubig ang customers na nawalan noong nakaraang araw," she said.

(We directed the water that was available to areas that really needed it for customers who experienced water interruption over recent days.)

"Alam kong hindi masaya 'yung mawalan ng tubig pero ito ay necessary evil para mapalawig pa 'yung serbisyo at lahat makatanggap ng tubig sa kanilang bahay," she said.

(I know it's not fun to lose water but this is necessary evil to broaden our services and ensure that all households will have water supply.)

• Manila Water says cutting water supply in some areas a 'necessary evil'

The mistakes could affect Manila Water's petition for rate hikes in 2022, Ty said.

"With regards to the rates [now], they cannot touch it anymore because it has already been approved," he said.

"But whatever happens now can be used in the 5th rate rebasing. Their quality of service, their actions going forward in solving this issue will affect their tariff adjustment," he said.

TY earlier said the water crisis in Metro Manila was the government's "fault."

"They're saying it's our fault. Yes, its our fault. It's everyone's fault because we have been delaying all these projects. Right now, we can't rely on Angat. It's just one source. We need an alternative water source and we need it yesterday," Ty told ANC's Headstart.

"It's the fault of the government because it is the responsibility of the government to source all this water. I would just like to make it clear that we are doing something about it," he said.

• MWSS: Water shortage government's 'fault,' solutions underway