TL;DR
A tent is never machine washed, because agitation and a spin cycle destroy the waterproof coating and can tear seam tape loose. Set it up or soak it in a tub with cool water and a technical fabric wash, sponge the dirty spots by hand, rinse thoroughly, and dry it completely in the shade before it goes back in the bag.
What is on a tent that you can ruin
Tent fabric is not just nylon or polyester. It has a coating, and that coating is the whole reason the tent keeps water out.
The rainfly and floor carry a waterproof coating, usually polyurethane or silicone-based, on the inside face. Machine agitation abrades it, spin cycles crease it, and hot water and harsh detergent break it down.
Seam tape is heat-bonded strip over the stitch lines. It peels when it is agitated, folded hard, or exposed to heat.
Mesh panels tear easily under machine agitation and snag on zippers.
Ultraviolet light is the tent's other enemy. A tent left pitched in full sun for weeks will weaken from sunlight alone, no matter how clean it is.
How do you clean a tent?
Set the tent up or fill a tub with cool water and a small amount of technical fabric wash. Sponge dirt off by hand with a soft cloth, working gently on coated surfaces. Rinse thoroughly with clean water, then let it dry completely in the shade before packing it away.
What to use, and what to avoid
Use: a technical fabric wash made for outdoor gear, or a very small amount of mild non-detergent soap. Cool water. A soft sponge or cloth. A soft brush for the floor.
Avoid: laundry detergent, which leaves residue that attracts water and defeats the coating. Bleach, which weakens fabric and strips coatings. Fabric softener, which coats fibers and destroys water repellency, explained fully in why fabric softener ruins technical outdoor gear. Stain removers with solvents. Hot water. A washing machine of any kind, including front-loading ones.
The step-by-step
1. Shake it out first. Get the pine needles, sand, and dirt out before water is involved. Turn the body inside out and shake.
2. Sweep the floor. A soft brush and a dustpan, or a shop vacuum on low.
3. Set it up if you can. Cleaning a pitched tent with a sponge and a bucket is easier and gentler than wrestling it in a tub.
4. Sponge the dirty areas. Cool water, a drop of technical wash, and a soft cloth. Work gently, especially on the coated inner face of a fly.
5. For a heavily soiled tent, tub soak it. Cool water and technical wash, submerged, twenty minutes or so, with gentle hand agitation. Not a machine.
6. Rinse thoroughly. Residue is worse than dirt. Rinse until the water runs completely clear.
7. Dry completely in the shade. Pitched, or hung over a line or a railing. Out of direct sun. Every surface, including the seams and the bottom of the floor.
8. Do not pack it damp. This is the single rule that matters most.
Why does my tent smell musty?
A tent packed away even slightly damp grows mildew, which shows as black or grey speckling and a persistent smell. Set it up, wash it with a technical fabric wash, rinse, and dry it fully. Mildew stains are usually permanent, and heavy growth can weaken the fabric itself.
Dealing with mildew specifically
Prevention is the only real answer. Once mildew has taken hold, you can remove the smell and some of the appearance, but not the stain.
Wash and rinse first, and dry fully. If the smell survives, gear-specific odor eliminators made for tents exist and are worth trying.
Do not use bleach on a tent. It weakens nylon and polyester and strips the waterproof coating, and it will not restore the fabric anyway.
Heavy mildew that has made the fabric feel weak or brittle means the tent is at the end of its life. That is a structural problem rather than a cleaning one.
Zippers, poles, and stakes
Zippers fail from grit, not wear. Rinse the zipper tracks with clean water and brush them with an old toothbrush. A dry lubricant made for zippers helps, and a stiff zipper usually just needs cleaning.
Wipe tent poles with a damp cloth, especially after coastal trips where salt corrodes aluminum. Dry them fully, and check the shock cord for looseness.
Rinse stakes, dry them, and pack them in their own bag so points do not perforate the fly.
Reproofing when water stops beading
A tent that wets through has usually lost its water repellency rather than its waterproof coating.
Test it with a spray of water on the fly. If the water soaks in rather than beading, a spray-on repellency treatment for tents restores it. Apply to a clean, damp fly per the product instructions.
Seam sealer is a separate product for lifted or leaking seam tape. Peeling tape can be trimmed and the seam resealed on the coated side.
A polyurethane coating that has gone sticky and flakes off is degrading, and that generally means replacement rather than a repair.
Source: Outdoor Industry Association gear care guidance and manufacturer care instructions
Storage is where tents die
Never store a tent tightly stuffed in its compression sack for months. Compression creases the coating along the same folds until it cracks.
Store it loosely in a large cotton or mesh bag, dry, somewhere cool and out of the sun. A closet is better than a garage attic, which cycles through extreme heat all summer.
Refold it differently each time you pack it so creases do not repeat in the same places.
The same loose, dry storage rule governs a sleeping bag in how to wash a down sleeping bag and most of the kit in our guide to cleaning outdoor gear and equipment.
The Oregon-specific problem
Camping through a wet season means a tent almost always comes home damp, and there is often nowhere dry to pitch it at home.
Set it up in a garage, a carport, or under an overhang with a fan running. Hang the fly separately over a railing.
A tent left rolled in a wet stuff sack for a week will grow mildew. That timeline is short, and it is why unpacking a tent the night you get home matters more than any washing method.
FAQ
Can you put a tent in the washing machine?
No. Machine agitation and spin cycles abrade the waterproof coating, crease it permanently, tear mesh, and peel seam tape. This applies to front-loading machines too. Clean a tent by hand in a tub or while it is pitched, using cool water and a technical fabric wash.
What soap can you use on a tent?
A technical fabric wash made for outdoor gear, or a very small amount of mild non-detergent soap. Avoid laundry detergent, which leaves a residue that attracts water, and avoid bleach, fabric softener, and solvent-based stain removers, all of which damage coatings and water repellency.
How do you get mildew out of a tent?
Wash it with a technical fabric wash, rinse thoroughly, and dry it completely, then try a gear-specific odor eliminator for any remaining smell. Mildew stains are usually permanent, and bleach is not a fix because it weakens the fabric and strips the coating. Prevention is the real answer.
How long does a tent take to dry?
A few hours pitched in a breeze, and up to a full day in humid conditions or indoors. Every surface must be dry, including seams, the underside of the floor, and the inside of the fly. Packing a tent even slightly damp is what causes mildew, so wait longer rather than guessing.
Should you store a tent in its stuff sack?
Not for long periods. Compression creases the waterproof coating along the same lines until it cracks. Store the tent loosely in a large cotton or mesh bag somewhere cool and dry, and use the stuff sack only for transport.
How do you know when a tent needs reproofing?
Spray water on the rainfly. If it beads and rolls off, the repellency is fine. If it soaks in and darkens the fabric, a spray-on tent repellency treatment applied to a clean fly will restore it. A coating that feels sticky or flakes off is degrading and means the tent is near the end.
Camping gear comes home wet and muddy and the house takes the hit. If keeping up with that part is what you would rather hand off, get a quote or read more about house cleaning services.