Canberrans could expect to see their gas bills drop by more than $100 next financial year if the price of gas remains unchanged and lower network costs are passed on to customers, the Australian Energy Regulator said on Thursday.

And business owners could enjoy a decrease of about $849.

The regulator oversees electricity networks and natural gas pipelines by every five years setting the maximum amount of revenue distributors can earn.

This includes the cost of operating and maintaining the network, which the regulator said fell on the back of improved market conditions since its last decision in 2011.

ActewAGL's capped revenue, at $301.4 million, was about 21 per cent less than its proposed revenue of $382.6 million.

But the energy distributor was at pains to explain the regulator's announcement of lower gas prices referred only to the network portion of gas bills, which account for about a third of a typical residential bill and small business bill.

The remaining two-thirds is the retail cost, which is set by energy retailers. Retailers must announce the price of gas two weeks before coming into effect on July 1.

ActewAGL's manager of gas networks, Ed Gaykema, said for a typical ACT residential customer using 45 gigajoules per year the regulator's decision would mean a fall in the network component of their gas bill of about $79.

For a typical small business customer using 200 gigajoules per year, this would mean a fall of about $338.

The regulator warned the expected price drops would happen only if other parts of the bill, such as gas prices, remained the same and the lower network distribution charges were passed onto consumers.

"The AER's role is to ensure that consumers pay no more than necessary for the safe and reliable delivery of gas by setting the overall revenue that businesses can recover from customers," board member Jim Cox said.

"The AER expects that retailers will pass through these savings. But we also urge consumers to shop around and take advantage of competitive retail market offers to ensure they get the benefits of [Thursday's] decisions."

Asked if ActewAGL would commit to passing on lower distribution charges, Mr Gaykema, said it was "required under the National Gas Laws to operate its gas business within the AER's final decision".

Australians spent an average of $11 each week on mains gas bills in 2012, according to the most recent Australian Bureau of Statistics data.

But ACT households spent almost double that, at about $21 each week, which is among the highest of all states and territories.

The regulator said although consumers could expect prices to drop next financial year, gas bills would rise, on average, 1.2 per cent each year.

ACT customers can compare offers on the regulator's EnergyMadeEasy website.