Getty Images

Utility workers at blast site in San Bruno on Sept. 13

When your gas bill goes up this year, do not blame the San Bruno pipeline explosion. 

The $120 million rate hike over the next four years approved by the California Public Utilities Commission on Thursday will hoist the average residential customer's bill an estimated 36 cents from $51.60 to $51.96 per month this year, an increase of .7 percent.

But charges could go up as high as $58.16 by 2014, the Oakland Tribune reported. 

PG&E requested the rate increase before the explosion that killed eight people and destroyed 38 homes last year. 

"To the extent the money goes toward safety or pipeline integrity, it's money they [PG&E] would have gotten regardless of San Bruno," said Mindy Spatt, a spokeswoman for The Utility Reform Network. 

The San Bruno explosion did have one effect on the regulators' decision, however. The California Public Utility Commission is requiring PG&E to report back to regulators on how it spends money designated for capital improvements on pipelines, for safety and reliability. 

"They can't shift money from safety to executive perks," said Spatt. 

And money that goes unspent could be returned to ratepayers. 

"If PG&E doesn't spend the money earmarked for integrity management programs, they would be required to refund the money back to customers," said Mark Pocta, program manager for the state's Division of Ratepayer Advocates. 

The battle over who will pay for any new safety measures required in the wake of the San Bruno explosion is yet to come. This September, the National Transportation Safety Board will release its report on the cause of the explosion, so stay tuned.