Can you use PEX or PVC pipe for a misting system?

Only where the water is at house pressure. PEX is rated 160 psi at 73F (23C) and 100 psi at 180F, which covers a hose-pressure misting line at 40-80 psi and the supply pipe to a pump, but not the outlet of a 160-250 psi booster. PVC starts higher (850 psi for 1/2 in Schedule 80 at 73F) and then loses most of its rating as it warms: at 120F it keeps 40%, at 140F 22%. A 1,000 psi plunger pump line needs tube rated above 1,000 psi at operating temperature, which in practice means rated nylon, hard-drawn copper or stainless steel. The tables below put the published ratings of each material side by side against the three misting pressure classes.

Why do some sources say PEX and PVC work?

Because the word "high pressure" means two different things. In house plumbing it means the top of the 40-80 psi range, and PEX and PVC are both comfortably rated for that; forum posts recommending PEX for a "high-pressure mainline" are talking about that scale. In misting it means 800-1,000 psi (55-70 bar) running for hours. Two more things blur the line:

• Burst is not working pressure. Plastic and copper pipe burst at several times their rated working pressure, and that margin is there for surges, not for continuous duty. Every rating on this page is a working pressure.
• Ratings are quoted cold. PVC's 590 and 850 psi, PEX's 160 psi and the nylon figures are all given at 73-75F. A misting line on a sunny fascia is not at 73F.

So both answers are right about different systems. PEX and PVC work on a low-pressure misting system. They do not work after a pump that makes real misting pressure, and with PVC the reason is mostly heat.

What pressure is each pipe and tube rated for?

The table collects working pressure ratings from the manufacturers' and standards bodies' own data, at the temperatures each source gives. The last three columns compare those ratings with each pressure class.

Working pressure ratings of misting candidates, from published data (read 2026-10-17)

Material and size	Rating when cool	Rating when hot	Low (40-80 psi)	Mid (160-250 psi pumps)	High (800-1,000 psi)
3/8 in LDPE misting line (DIG OB07)	Up to 80 psi	Not published	Yes	No	No
PEX, any size (ASTM F876, Uponor AquaPEX)	160 psi at 73F	100 psi at 180F; 80 psi at 200F	Yes, out of sun	No	No
1/2 in Schedule 40 PVC	590 psi at 73F	236 psi at 120F; 130 psi at 140F	Yes	Marginal; fails a 250 psi pump when hot	No
1/2 in Schedule 80 PVC, solvent welded	850 psi at 73F	340 psi at 120F; 187 psi at 140F	Yes	Yes below about 120F	No
1/2 in Schedule 80 PVC, threaded	425 psi at 73F	170 psi at 120F	Yes	No	No
3/8 in OD high-pressure nylon 12 (Exlon HP375075)	1,100 psi at 75F	Not published; 176F long-term limit	Yes	Yes	Yes, with a 10% margin when cool
3/8 in OD soft copper coil (ACR, annealed)	984 psi at 100F	836 psi at 150F	Yes	Yes	Just under 1,000 psi
3/8 in OD Type L copper, hard drawn (nominal 1/4 in)	1,569 psi at 100F	1,569 psi at 200F	Yes	Yes	Yes, if the joints match
3/8 in x 0.035 in stainless steel (ASTM A269)	3,300 psi at 100F	3,300 psi at 200F (factor 1.00)	Yes	Yes	Yes

The PVC hot figures are Harrison's 73F ratings multiplied by its own de-rating factors (0.40 at 120F, 0.22 at 140F), and the threaded line applies its rule that threading "requires a 50% reduction" in rating. The copper figures are the Copper Tube Handbook's calculated ratings: Table 14.3e for annealed ACR coils and Table 14.3b for Type L, whose nominal 1/4 in size has a 0.375 in outside diameter and a 0.030 in wall. Stainless is Swagelok's figure for 3/8 in by 0.035 in tubing, which it multiplies by 1.00 at 200F for both 304 and 316.

How hot does water in a misting line get?

Hot enough to matter for every plastic in the table. In a 2021 study of garden hoses left in sun, water in the hoses "reached a temperature of up to 47.3°C" (117F) on grass at an air temperature of 35C (95F), and 49.8C (122F) on concrete at only 28.5C (83F) air. That was within about three hours of sun. A misting line mounted under a south or west eave sees the same sun every afternoon of the season it is used in.

So the useful design temperature for an exposed line is about 120F, not the 73F printed on the pipe. At 120F the PVC factor is 0.40, which is why a pipe rated 590 psi on the label is a 236 psi pipe on a hot afternoon. Harrison's sheet sets 140F as the maximum service temperature for PVC, and the surface of a dark green PVC hose in the same study measured 57.8C (136F). The cold water article covers what that heat does to the first bursts of mist, and water hygiene and Legionella covers what it does to water left standing in the line.

Where does PEX fit in a misting system?

Upstream of the pump, or as the whole distribution line of a hose-pressure system. Uponor rates its AquaPEX at 160 psi at 73F, 100 psi at 180F and 80 psi at 200F, and for domestic hot water says operating conditions "should not exceed 140°F (60°C) at 80 psi." HUD's materials release for the same product says it "may also be used in irrigation systems." Both fit a 40-80 psi misting supply. Three limits apply:

• Sunlight. The HUD release states that PEX "shall not be exposed to direct sun light for more than 30 days." An eave-mounted misting line is in sun for years. Bury PEX, run it inside a wall, or sleeve it; do not use it as the exposed line that carries the nozzles.
• Size. PEX is sized like copper water tube: Uponor's 1/2 in pipe is 0.625 in OD with a 0.475 in bore. Misting nozzle tees and slip-lock fittings are made for 3/8 in OD tube, so PEX does not take them directly.
• Pumps. A mid-pressure booster in the 160-250 psi class can exceed PEX's 160 psi rating even at 73F. Nothing after a pump outlet should be PEX.

Is PVC safe on a mid-pressure misting pump?

Schedule 80 can be, shaded and solvent welded; Schedule 40 often is not. The mid-pressure systems guide puts most booster pumps in the 160-250 psi class, and the line has to be rated for the pump's maximum pressure, not the pressure it settles at with nozzles open, because a pump that dead-heads against closed nozzles or a clogged line reaches its shutoff point. Harrison adds two rules that rule out common shortcuts: threading Schedule 40 "is not a recommended practice due to insufficient wall thickness," and solvent cemented joints "should be utilized when working at or near maximum temperatures."

For low-pressure systems PVC has an advantage none of the others share: a large bore. A 1/2 in PVC main carries far more flow than 1/4 in or 3/8 in tubing, which is why the longest kit-rated line in how long a misting line can be is a 1/2 in PVC kit.

What should a 1,000 psi misting line be made of?

Tube rated above 1,000 psi at the line's working temperature, and three entries in the table are rated above 1,000 psi: hard-drawn copper (1,569 psi, unchanged to 200F), stainless steel (3,300 psi, unchanged to 200F) and high-pressure nylon (1,100 psi, at 75F only).

Nylon is the closest call. Exlon's HP375075 misting tube is rated 1,100 psi working and 2,800 psi burst, both at 75F, with a long-term limit of 176F in air; Pexco lists its HP 375075 nylon 12 tube at 2,800 psi burst and adds that the figures are "a general reference only." Neither sheet publishes a temperature derating, and a 1,100 psi rating only has to lose 10% to drop below 1,000 psi. The one nylon 12 maker read for this page that does publish a curve, SMC for its pneumatic T series, rates its tubing at about 70% of its room-temperature pressure at 40C (104F) and about 50% at 60C (140F). That is a different product, but it is the reason to shade nylon, set the pump no higher than it needs, and ask the tube supplier for a rating at temperature. The misting tubing types guide covers UV, sag and clip spacing for nylon.

Copper is the surprise. The soft copper coils many installers bend around a patio are annealed, and the Copper Tube Handbook's calculated rating for a 3/8 in OD annealed coil is 984 psi at 100F and 836 psi at 150F: under a 1,000 psi system by the handbook's own method. Burst pressures are many times higher, and the handbook calls its ratings "very conservative," so this is a rating gap, not a predicted failure. It still means a pump set to 1,000 psi on soft copper runs above the tube's rated working pressure. Hard-drawn tube of the same diameter is rated 1,569 psi, and brazing it gives that back: the handbook says that when brazing or welding, "the annealed ratings must be used," because the heat softens the tube.

Do fittings change the answer?

Often they decide it. The Copper Tube Handbook says that "the lower of the ratings (tube, fitting or joint) will govern," and its joint tables show how far below the tube a joint can sit:

Copper joint ratings from the Copper Tube Handbook, Tables 14.4a and 14.4b

Joint	Rated pressure	Misting class it can serve
Push-connect fitting (1/2 to 2 in)	0-200 psi	Low only
Press-connect, general piping (1/2 to 4 in)	0-200 psi	Low only
Press-connect for high-pressure HVACR (1/4 to 1 1/8 in)	0-700 psi	Low and mid
95-5 tin-antimony solder, 1/8 to 1 in, 100F	1,090 psi	High, cool only
95-5 solder, same sizes, 150F	625 psi	Low and mid

The same logic applies to every material. The push-to-connect fittings sold at hardware stores for PEX and copper are house-pressure fittings. A misting line is only as strong as its weakest tee, nozzle adapter or pump outlet hose, which is why the high-pressure systems that last use compression or slip-lock fittings made and rated for misting. When a joint does weep, leaking fittings walks through the causes, and nozzle threads and fittings covers what the nozzle end screws into.

When does this advice stop applying?

• Other brands and grades. The PVC factors are Harrison's, the PEX ratings Uponor's, the nylon ratings two makers'. Other brands, PVC fittings, CPVC and other nylon tubes have their own sheets. Use the sheet for the product you buy.
• Cold climates. Ratings only rise as water cools, but freezing is a separate failure for rigid pipe. Drain everything before frost, as in winterizing a misting system.
• Fog systems above 1,000 psi. At 1,500 psi only stainless keeps a wide margin: hard copper (1,569 psi) barely clears it, and the nylon in the table is rated 1,100 psi.
• Codes. The supply side needs backflow protection whatever it is made of, and local code decides the device; see water supply and filtration.

For the rest of the build, from tubing routing to commissioning, start at the installation section.