When Joe Porter, a 29-year-old video editor, moved into his 400-square-foot studio apartment in Los Angeles four years ago, his bills for water, trash removal and pest control were bundled together into one monthly payment that came out to about $60. After the first few years, Porter said, his bill increased to about $200.

When he asked his landlord – the giant real estate investment trust Equity Residential — for an explanation, he was told billing was done by a third party and that Equity could not provide a more detailed breakdown. Like many landlords of multifamily buildings, Equity uses a billing method called ratio utility billing systems (RUBS). Landlords who use this system divvy up the costs of the building’s total utilities usage according to each unit’s square footage and number of tenants.

Porter had no luck getting more of an explanation from Equity. “Because I was on my own, management didn’t pay any attention to me,” Porter says.

But late last year, Porter and others who live in Virgil Square Apartments formed a tenant association and began organizing their neighbors. After launching a RUBS strike in June that involved dozens of tenants refusing to pay the bundled utility bills, they’ve secured some big wins.

Equity agreed in August to decrease tenants’ monthly RUBS bills, acknowledged that the tenants were being overcharged and issued a total of $25,000 in refunds. But tenants are still on strike, as their demands include Equity providing a breakdown of the underlying utility costs and the formula it uses to calculate bills. They are also pushing the city to mandate that landlords be more transparent in tenant utility bills.

Porter attributes the strike’s success thus far to collective action. “The only way we accomplished that was by organizing, by collectively making noise, collectively withholding payments and doing it together. Because individuals have tried stuff like this, and management has not responded at all,” Porter says.