The codes allow as little as 750 GPM fire flow for average sized 1-family detached homes. Since fire flow is the major factor in water main size, lower fire flows nearly always mean smaller mains. Lower fire flow also means smaller storage tanks and less pump capacity. All of these reductions can add up to a significant cost savings. For example, when Scottsdale, Arizona adopted a residential sprinkler ordinance, the estimated savings in water costs was 7 million dollars.