After 15 years of selling gas to account holders at below Vashon’s prevailing prices, Williams Heating has opened its gas station to the general public.

The station south of town, owned by Islanders Dennis and Janet Williams, has long offered gas at rates significantly lower than Vashon’s two main gas stations. However, many have opted not to fill up at Williams because doing so requires setting up an account and paying a monthly bill.

Dennis Williams said a recent change in pumps, however, means the station can now accept debit and credit cards as well, though not cash.

“Our mission is to give people on the Island another option and to offer the product as competitively as we can,” Williams said.

As of Monday, Williams Heating was selling regular, unleaded gasoline for $3.99 per gallon — 50 cents cheaper than Chevron, which listed regular gas at $4.49. Williams was also 30 cents cheaper than 76, which listed regular at $4.29. The average price in Seattle on Monday was $3.66, according to Seattlegasprices.com.

Williams said he recently put a sign by the road that lists his prices and says the station now accepts debit and credit cards, and he’s noticed an increase in business.

“I think customers are happy,” he said. “It’s one less card they have to have, one less bill to get in the mail.”

Williams said the low price was not an introductory one. While the price of gas will continue to fluctuate, he said, he intends to keep the same margins. In addition, the station will soon begin to offer a discount of five to 10 cents per gallon to debit card users — a discount Williams said reflects the lower price the station pays to process debit cards compared to credit cards.

Williams said the change was made possible when he recently purchased new pumps for the station. The former pumps, 15 years old, read only the gallons pumped and not the price charged and by law could only be used by those who held accounts with Williams.

The new pumps, like most modern pumps, read both the gallons pumped and price charged and can therefore serve the general public. Williams Heating also sells heating oil and diesel for residential and commercial use.

When asked how he was able to offer gas prices lower than the other two gas stations in town, Williams said his markup was a business decision and he couldn’t speak for the other stations.

“The price that we’re offering is our intended margin. What the other stations do with their margin, who knows. They may decide to follow suit or not,” he said.

Williams said that with the transition to new pumps, he’s also installing a generator at the gas station so it can stay in business during a power outage.

During outages in recent years, both stations in town have been unable to pump gas. Williams Heating employees have manually filled Islanders’ gas cans, a process Williams called a huge effort and cumbersome. Williams, noting his family has a long history on the Island, said the installation of a generator was a move he thought would help Vashon.

“We thought it was appropriate to do for the Island,” he said. “There is a need for it, and we decided to step up and fill that need.”