Two days after the failure of five water mains early Saturday morning, Belmont Public Works Department and the Massachusetts Water Resources Authority are working to discover the cause or causes for the system failure that left nearly 500 households with no water service or little pressure.  

But according to a MWRA spokesman, the state authority which supplies 61 communities in eastern Massachusetts with water is not at fault.

"[The] MWRA did NOT have any pressure spikes yesterday," Spokeswoman Ria Convey wrote in an email to Belmont Patch Sunday afternoon, referring to the possibility that a spike in pressure in the water system resulted in the 80 to 90 year old pipes to rupture. 

In fact, the blame, in the view of the authority, lies squarely with the town.

"The water main breaks were caused by a valve that was left partially opened within Belmont's system," stated Convey.

But according to Peter Castanino, Belmont's Public Works director, the jury is still out on the cause or causes for the multiple failures to occur nearly simultaneously across town.

"[The town and the MWRA] are working together and matching up all the information we have so we can avoid this from happening in the future," said Castanino. 

When asked about the MWRA's claim that an open valve in Belmont caused the damage to the water mains, Castanino said from his initial investigation, "nothing definitive" has been uncovered to lay blame on a single act. 

"I hope to have a possible reason in a couple of days," said Castanino. 

Currently, the town has back filled the roadway at most locations and will restore the streets in the near future.

Breaks occurred in Belmont Center, the Franklin Road in the Waverley neighborhood and Brighton and Oliver streets in the Winn Brook area.

The fix in Belmont Center is a bit more complicated as a storm drain was also damaged and the DPW will need to determine if it is an active or dormant drain. A couple of steel plates cover the drench DPW crews dug Saturday as workers will be entering the hole to investigate the break's severity. In addition, small portions of Leonard Street buckled due to the rush of water and will need to be reconstructed. 

A complete repair at each site will be determined by cost and the availability of firms to do the restoration, said Castanino.