Does hot water have to reach a restaurant sink in 45 seconds?

The guide states the rules in two sentences. The first says the heater must be sized to furnish "a continuous supply of hot water, at a thermostat set-point of at least 120ºF, to all hand sinks, dish/utensil sinks, mechanical warewashing machines, rinse sinks, service sinks, garbage can washers, shower heads, similar equipment, and other plumbing fixtures that utilize hot water, within 45-seconds at all times."

The second sets the distance: "The maximum developed length of piping between a hot water or tempered water supply source and all fixtures or appliances served by the supply source shall not exceed 60 feet for incorporated areas, or 50 feet in unincorporated areas of Maricopa County."

Put together, that gives you the working numbers:

• Time: 45 seconds from opening the tap.
• Temperature at the fixture: at least 110 degrees F, or the required temperature for that fixture. The guide defines hot water as water "at a temperature equal to or greater than 110ºF."
• Distance: 60 feet of pipe in an incorporated city or town, and 50 feet in unincorporated county areas.

Developed length is a plumbing term for the full run of pipe as installed, including turns, not the straight-line distance on the floor plan. Ask your plan reviewer how the county measures it on your drawings.

### Why the county cares

Warm water helps people wash. The guide says "an adequate flow of warm water will cause soap to lather and help flush soil quickly from hands and equipment." It also says that "inadequate pressure could result in improper hand washing or equipment operation." The FDA Food Code sets the goal at the federal level. Section 5-103.11 says "hot water generation and distribution systems shall be sufficient to meet the peak hot water demands throughout the FOOD ESTABLISHMENT." The 45 second limit is the county's way of testing that a system works at the far end and not just at the tank.

When you open a hot tap that has not been used for a while, the water in the pipe is cold. It has to be pushed out before hot water arrives. A longer or wider pipe holds more cold water, and a slower flow takes longer to clear it. That is the reason for the distance limit. It keeps the wait short without needing a special system.

A hand sink is the worst case. Its faucet may run at a low flow, and hand sinks are often the farthest fixtures from the heater. A hand sink on a mixing valve also has to reach the 100 to 110 degrees F range. Our page on the water temperatures required in a commercial kitchen covers the tempering side.

### What to put on the plans

Reviewers work from drawings, so the fix is cheapest on paper. The county guide says each establishment needs "its own properly sized dedicated hot water supply source," and that the heater, tempering devices, recirculation pumps and mixing valves all "require final on-site evaluation and approval prior to use." Three details help a plan get through:

• Show the heater location and the pipe route to the farthest sink, with the run length marked.
• Mark every hot water fixture, including bar sinks, mop sinks and hose reels, since the rule covers "all fixtures or appliances served by the supply source."
• Show the fix where a run is long, such as a recirculation loop or a second heater near the far fixtures.

A tenant in an existing space has the same problem in reverse. If the heater is old and the layout is fixed, the loop or a point-of-use heater is usually the fix. Our page on commercial tenant improvement plumbing covers what to expect when a space is remodeled.

The guide lists the fixes it accepts or prefers. They run from simple to more complex.

1. 1Move or add a heater. The guide says "where practical, the Department recommends installing separate point-of-use water heaters for remote fixtures or appliances, such as lavatories in school restrooms." Our page on point-of-use water heaters explains what those are.
2. 2Add a recirculation loop. "The installation of a recirculation pump may be required to ensure that water reaches the sink fixture or appliance at a temperature of at least 110ºF or the required temperature within 45 seconds." The guide also says it "recommends that hot water systems be designed to recirculate water." Our page on whether a recirculation pump is worth it covers how a loop works, and instant hot water at every faucet covers the comfort side.
3. 3Insulate the pipe. The guide recommends that circulating hot water systems "be insulated in accordance with the International Energy Conservation Code."
4. 4Shorten the run. Moving the heater, or the fixture, closer on the plans is the cheapest fix if it is done before rough-in.

### What the county discourages

The guide is cautious about shortcuts. It says "the installation of a heat trace/self-regulating tape system to supply tempered water to long lengths of piping run is strongly discouraged." Heat trace can be used "if necessary to reduce stagnation and the growth of microorganisms in the water," but it requires "final on-site evaluation and approval." It also says "the installation of timers on water heaters is not recommended." A timer saves energy but can leave a kitchen without hot water at the wrong moment.

Long pipe runs and slow use create another concern. The guide warns that "large water heater systems frequently contain tepid zones, scale and sediment accumulations, 'dead leg' sections of plumbing, non-recirculation plumbing lines, and temperatures maintained below 140°F." Those conditions are the ones Legionella bacteria like. It recommends that designers "eliminate or minimize 'dead legs' in plumbing lines, when possible, to reduce stagnation." So a recirculation loop does two jobs. It shortens the wait for hot water, and it keeps water moving. Our page on Legionella water management plans goes into the health side.

For an example of how one maker's pumps decide when to run, see Grundfos COMFORT pump control modes.

You can check a fixture yourself in a few minutes.

1. 1Pick the farthest hot water fixture from the heater. That is usually a hand sink or bar sink.
2. 2Let the line sit unused for a while, so the pipe is cold.
3. 3Start a stopwatch and open the hot tap fully.
4. 4Read the temperature with a thermometer in the stream. The county measures at the faucet.
5. 5Stop the watch when the water reaches the required temperature. If it is more than 45 seconds, the fixture does not meet the county's standard.

If it fails, the next step is a plumber's look at the run, the pipe size and the heater location. HQ Plumbing & Air is licensed and insured, and can check your hot water timing and tell you which fix fits the building. We offer free estimates and upfront pricing.