Can you run a misting system from a water tank?

Yes, a misting system can run from a water tank, but how depends on the pump. A high-pressure plunger pump head will run on a flooded inlet, meaning a tank whose water level sits above the pump, so a tank on a stand can feed it directly. Most packaged misting pumps, though, carry a low-pressure safety switch that wants 30-35 psi at the inlet, and gravity cannot supply that. Those pumps need a booster pump between the tank and the misting pump. This page shows how to tell which kind you have, how to plumb each, and how long a tank lasts.

Why do some sources say a misting pump cannot use a tank?

Because two different parts of the pump have two different requirements, and most advice only describes one. The usual rule on this site and elsewhere, that a plunger pump needs about 20-60 psi of inlet pressure, describes how a pump performs best and what its controls expect. It is not a statement that the pump head cannot fill from a tank.

Cat Pumps, whose pump head AMS lists as a feature of its misting pumps, puts it plainly in its inlet check-list: optimum performance comes with +20 psi inlet pressure, but "with adequate inlet plumbing, most pumps will perform with flooded suction." Advanced Misting Systems (AMS) lists its bare 1,000 psi direct-drive pumps, open and enclosed, at an inlet range of "Flooded-60 PSI." The pump head is fine with a tank.

The packaged pump is what refuses. The table collects what one maker's own manuals say across its range:

Inlet requirements in Advanced Misting Systems pump manuals (read 2026-10-07)

Pump	Inlet requirement as published	Tank feed
Direct drive open, 60030K-60151K (0.33-1.5 GPM, 1,000 psi)	Flooded-60 psi; low water pressure cut-out switch sold as an option	Gravity feed possible
Totally enclosed, 60030KH-60201KH (0.33-2.1 GPM, 1,000 psi)	Flooded-60 psi; cut-out switch optional	Gravity feed possible
Models with the low-pressure switch fitted (combined 1,000 psi manual)	Troubleshooting: "Make sure the inlet water pressure is over 35 PSI"	Needs a booster
HDE variable speed, 600100-HDE-1PH-120 VFD	30-60 psi	Needs a booster
300 psi mid-pressure pump, 52300-KH	30-60 psi	Needs a booster
Pro Mist 35, F10-04-003 (0.2 GPM, 1,000 psi)	"At least 30 psi for continuous operation"; cutoff switch lights a warning on low inlet pressure	Needs a booster
Cool Caddie portable misting fan	Built-in 16 gallon tank; low water level indicator	Designed for it

The same maker's manual explains the pattern. Under "Motor will not turn on" it warns that deionized or reverse osmosis supplies "can be problematic for the low-pressure safety switch," and under "Pump chatter" it names the switch "not getting the correct amount of water pressure and rapidly turning the pump on and off." A tank feed is the same situation: enough water, not enough pressure for the switch.

Can you raise the tank high enough to get the pressure?

Not in any practical setup. Water gives 0.433 psi per foot of height above the pump inlet:

Gravity head from a tank above the pump (0.433 psi per foot)

Water level above pump inlet	Inlet pressure	Enough for
3 ft (tank on a low stand)	1.3 psi	A pump rated for flooded inlet
6 ft (stand plus a full drum)	2.6 psi	A pump rated for flooded inlet
46 ft	20 psi	Cat's optimum inlet pressure
69 ft	30 psi	The 30-60 psi pumps above
81 ft	35 psi	The 35 psi switch threshold

A tank on a stand gives a flooded inlet and nothing more. That is all a flooded-rated pump needs, and nowhere near what a switch-protected pump needs.

How do you gravity-feed a pump rated for a flooded inlet?

With a flooded inlet there is almost no pressure to spare, so every restriction between tank and pump matters more than it does on a hose bib. Cat's check-list sets the rules:

1. Put the tank's outlet above the pump inlet. The water level must stay above the pump all the way down, so the usable volume ends at the outlet, not at the tank floor.
2. Use a bigger, flexible inlet line. Cat says the line "must be a minimum of one size larger than the pump inlet fitting" and "MUST be a FLEXIBLE hose, NOT a rigid pipe." Keep it short, with no elbows if you can.
3. Filter without starving. The 5 micron sediment filter still belongs before the pump, but on 1-3 psi of head a loaded cartridge stops flow long before it would on house pressure. Size the housing generously and change cartridges early.
4. Protect against an empty tank. A pressure cutoff set for house pressure will never close on a gravity feed. Use a float or level switch in the tank that cuts the pump, which is how the tank-fed Cool Caddie works: its manual describes a "low water level indicator," and its maker says built-in safety switches prevent dry running.
5. Return bypass to the tank, not the drain. Cat recommends directing bypass "to a baffled reservoir tank, with at least one baffle between the bypass line and the inlet line," so returning water does not carry air straight into the pump.

On reservoir size, Cat's figure is "generally a minimum of 6 to 10 times the GPM," which for a 0.5 GPM misting pump is only 3-5 gallons. That minimum keeps the inlet calm; runtime, below, is what sets the real size.

How do you feed a switch-protected pump from a tank?

Put a small booster pump between the tank and the misting pump, so the misting pump sees the pressure it would get from a hose bib. The order is tank, strainer, booster, 5 micron filter, misting pump. The same component order from a house supply is in water supply and filtration, which also explains why a tank filled through an air gap is the most complete backflow separation there is.

Choose the booster on four numbers:

• Output pressure at or above the misting pump's minimum, with margin for the filter: at least 35-40 psi for a pump that wants "over 35 PSI."
• Flow above the misting pump's rating, not the nozzles' total. Cat says supply "should exceed the maximum flow being delivered by the pump," and the Cool Caddie manual asks for a fill supply of 1 GPM or more for a pump running five nozzles.
• Suction lift if the tank sits below it. Grundfos lists its SCALA boosters at up to 8 m (26 ft) of lift and recommends a foot valve with a strainer; Pentair lists Shurflo 8000 Series diaphragm pumps as self-priming "up to 8 vertical feet."
• Run limits. Household boosters assume taps that open and close. Grundfos's data booklet gives the SCALA2 a maximum runtime function that can turn it off after 30 minutes of continuous running, and lists SCALA1 at 25 starts and stops per hour. A misting pump drawing steadily all afternoon looks like a leak to the first; a cycle timer at 1 minute on, 1 minute off asks 30 starts an hour of the second. Check both before you buy, and see controllers, timers and humidistats for cycle settings.

A mid-pressure diaphragm pump can often skip the booster, because many self-prime and draw straight from a tank, which is why the mid-pressure systems guide recommends them for portable setups. Check the inlet line all the same: AMS's own 300 psi pump wants 30-60 psi. A hose-pressure kit is the opposite case: from a tank, the booster is the system's only pressure source and must deliver the 40-80 psi that low-pressure misting systems run on.

How long will a tank run a misting system?

Divide the usable gallons by total nozzle flow in gallons per hour. Nozzle flow, not pump rating, is what leaves the tank when bypass returns to it. The table uses this site's planning flows at 1,000 psi (0.008 in nozzle about 0.96 GPH, 0.012 in about 1.5 GPH) and 0.5 GPH for hose-kit nozzles.

Hours of continuous misting per full tank (MistGuide calculation, bypass returned to the tank)

System	Water use	16 gal	55 gal drum	275 gal tote
Portable fan, 5 x 0.008 in at 1,000 psi	4.8 GPH	3.3 h	11.5 h	57 h
Hose kit, 20 x 0.5 GPH (booster-fed)	10 GPH	1.6 h	5.5 h	27.5 h
Patio, 16 x 0.008 in at 1,000 psi	15.4 GPH	1.0 h	3.6 h	17.9 h
Patio, 20 x 0.012 in at 1,000 psi	30 GPH	0.5 h	1.8 h	9.2 h

The first row can be checked against a real product. The Cool Caddie FTC-P-18-5 runs five 0.008 in nozzles from a 16 gallon tank, and its maker lists "approximately 4 hours" on the product page and "3-4 hours, depending on the on/off cycle settings" in the manual. The calculation gives 3.3 hours of continuous misting, so the planning flow holds up. Your own nozzles may differ by a lot, because published charts for the same orifice disagree by up to about 40%; time one into a container as described in orifice sizes and flow rates, then use the water use and cost calculator for your own hours.

What water should go in the tank?

Cold potable water. AMS's pump manuals say to feed the system "with potable cold water supply only," and the Pro Mist 35 manual caps inlet water at 120 F. Two tank-specific problems follow:

• Stagnant, warming water. A tank is a store of standing water, the condition hygiene guidance warns about for misters. The Cool Caddie manual tells owners to drain the tank completely because "draining the water prevents formation of algae." Empty and rinse the tank between sessions, keep it shaded and covered, and follow water hygiene and Legionella for disinfection.
• Rainwater. CDC says rainwater "can contain germs and chemicals that could make you sick" even when it looks clean, and lists watering plants you do not eat and washing items not used for food as its safe uses. Misting over people puts the water on skin and in the air they breathe, which we read as outside those uses. Keep rain barrels for plant misting, and even there the propagation mist guide warns that holding tanks can carry pathogens onto cuttings.

When does this advice stop applying?

• Pumps that forbid tanks. Some manuals say no reservoir, full stop. Their warranty language wins over anything here.
• Tanks below the pump with no booster. Cat's check-list treats suction feeds as a special case needing reinforced hose; no misting pump manual read for this page approves suction lift for a plunger head.
• Battery and solar setups. A booster draws power too. Solar and battery power for misting pumps adds it to the energy budget.
• Freezing weather. A tank, booster and filter housing are three more things to drain.

For the rest of the supply side, from hose bibs to backflow devices, start at the installation section.