A hired carpet cleaning machine can do a respectable job on a synthetic carpet, as long as you use it the right way. The rules that matter most are simple: vacuum thoroughly first, use less detergent than you think, make more dry passes than wet ones, finish with clean water, and get the carpet dry the same day. Almost every bad result from a hire machine comes from breaking one of those five rules, not from the machine itself.
This guide takes you through it step by step, from what to check before you collect the machine to what to do if the carpet is still damp the next morning. If you are still deciding whether to hire a machine at all, our comparison of professional cleaning versus hiring a machine covers that question first.
Before you hire: three things to check
1. What your carpet is made of
Hire machines are designed for synthetic carpet, which is what most South African homes have: nylon, polyester or polypropylene. They are a poor match for wool and wool-blend carpet, which holds water deep in the fibre, reacts badly to high-pH detergents and is easily over-wetted. Check the label on an offcut if you have one, or the paperwork from when the carpet was fitted. Our guide to identifying your carpet fibre helps if you have neither. If it is wool, our guide to cleaning a wool carpet at home is the better starting point.
2. The condition of the machine
Before you take it home, look at both tanks, the brushes and the nozzle. The dirty water tank should be clean and should not smell, because a tank that was put away wet will put that smell into your carpet. The brushes should turn freely and be free of hair and threads, and the clear nozzle at the front should not be cracked, because a crack is a leak in the suction and suction is what gets the water back out.
3. The detergent
Use a low-foam carpet detergent made for extraction machines. Never put washing-up liquid, laundry detergent, bleach or a household spray into the tank. Washing-up liquid in particular foams far more than a machine can recover and leaves the pile sticky. If you are choosing a spotter for stains as well, our guide to the cleaning products that damage carpet is worth reading first.
Step by step: using the machine
Step 1: Clear the room
Move out as much furniture as you can. Anything too heavy to move gets a square of foil or a plastic tab under each leg, so that wet wood stain or rusting metal feet cannot mark the damp carpet.
Step 2: Vacuum slowly, twice
This is the step people rush, and it matters more than the machine. Most of the soil in a carpet is dry grit, and dry grit is far easier to remove dry than wet. Once water hits it, it turns to mud that sinks to the base of the pile. Vacuum slowly in one direction and then again at right angles, and do the edges with the crevice tool, where fine dust collects against the skirting. Our guide to the correct way to vacuum a carpet has more.
Step 3: Test in a hidden corner
Mix a little detergent at the label dilution, apply it to a hidden area such as inside a cupboard, wait a few minutes and press a white cloth onto it. If colour transfers to the cloth, stop. The dyes in that carpet are not stable enough for a wet clean at home.
Step 4: Pre-treat and let it dwell
Spray the walkways, the area in front of the couch and any spots with diluted detergent, and leave it for 5 to 10 minutes. Do not let it dry. That waiting time is when the chemistry loosens the soil, and skipping it is why a machine seems to “just move the dirt around”. Work it in gently with a soft brush if you have one. This is the same order we follow on every professional clean: chemistry first, time to work, then agitation, and only then the rinse.
Step 5: Fill the tank with cool to lukewarm water
Use tap water, not water from the kettle. Very hot water can set protein stains, make dyes run, and on some carpets soften the adhesive that holds the backing together. If you are pre-treating properly, you do not need hot water at all; we clean with normal-temperature water ourselves for the same reasons. Add detergent at the label dilution or slightly below it.
Step 6: One slow wet pass, then two dry passes
Start in the corner furthest from the door so you never have to walk back across wet carpet. Work in strips about a metre long. Squeeze the trigger and pull the machine slowly towards you for one wet pass, then release the trigger and pull it back over the same strip at least twice more. Those dry passes are where the water comes back out, and the more water you recover the faster the carpet dries and the less residue it holds. Slow is the key word: a machine pulled quickly recovers very little.
Step 7: Empty the dirty tank often
When the recovery tank is nearly full, the machine stops picking up and starts leaving water behind. If you see foam building up in the tank, empty it and use less detergent in the next fill.
Step 8: Finish with clean water only
Once the whole room is done, empty both tanks, fill the clean tank with plain water and go over the carpet once more with a wet pass and two dry passes. This rinse is what stops the carpet from re-soiling. It is the reason our own extraction uses clean water only, with all the chemistry kept in the pre-spray: chemistry left in the pile is what makes a carpet go grey again within weeks. We explain the mechanism in why carpet gets dirty again quickly after cleaning.
Step 9: Groom and dry
Brush the pile in one direction so it dries standing up rather than flattened. Open every window you can, run a fan across the floor, and keep people and pets off the carpet until it is dry. On the Highveld, a dry winter day with a breeze will dry a well-extracted carpet surprisingly quickly; a humid summer afternoon with the windows closed will not.
The mistakes that cause most bad results
- Too much detergent. It does not clean more, it just leaves more behind.
- Too many wet passes. If a stain will not move, more water will not move it either. It soaks the underlay, and a soaked underlay takes days to dry.
- Going over pet urine with a wet machine. Water reactivates the salts urine leaves in the backing, and the smell often gets worse. Urine needs an enzyme or specialist treatment first; see enzyme versus regular cleaners for pet stains.
- Using it on a rug on a wooden floor. The water goes straight through and into the timber.
- Stairs with the full-size head. Use the hand tool and very little water. Stair carpet is wrapped tightly over the nosing, and over-wetting it can loosen it. Our guide to cleaning carpeted stairs covers the technique.
When to stop and call a professional
Stop if colour comes off on your test cloth, if the carpet is still wet after 24 hours, if brown marks appear as it dries, if the carpet starts to ripple or lift at the seams, or if a smell is getting stronger rather than weaker. Each of those is a sign that the carpet needs a different method, and carrying on with more water usually makes it worse. There is more on these problems in why carpet smells musty after cleaning and delamination and shrinkage from over-wetting.
A hire machine is a good tool for freshening a lightly soiled synthetic carpet between professional cleans. For a carpet with pet urine, set-in stains, heavy traffic lanes or a wool pile, a professional clean is the better route, and our carpet cleaning page explains what ours includes.
Common questions
How do you use a hired carpet cleaning machine properly?
Vacuum the carpet slowly in two directions first, test the detergent on a hidden corner, and pre-treat traffic lanes and spots, leaving them to dwell for 5 to 10 minutes without drying out. Fill the clean water tank with cool to lukewarm tap water and use no more detergent than the label says, or less. Work in small sections from the far corner towards the door, making one slow wet pass and then at least two dry passes with the spray trigger released. Finish with a rinse pass using clean water only, empty the dirty water tank whenever it is nearly full, and ventilate the room hard so the carpet dries the same day.
How much detergent should I put in a hired carpet cleaner?
No more than the dilution on the label, and on a carpet that has been cleaned before, often less. Extra detergent does not clean more: whatever the machine cannot recover stays in the pile as a sticky residue, and that residue attracts dirt so the carpet looks worse within weeks. A final pass with clean water only, no detergent at all, is the single most useful thing you can do to prevent it.
Should I use hot water in a carpet cleaning machine?
Cool to lukewarm tap water is the safer choice. Very hot or boiling water can set protein stains such as blood, milk and urine, can make unstable dyes bleed, can shrink or felt wool, and on some carpets can weaken the adhesive that holds the backing layers together. The cleaning is done by the detergent, the dwell time and the agitation, not by the temperature of the water.
How long does carpet take to dry after using a hired machine?
With good technique and good ventilation, most synthetic carpets should be dry within 6 to 12 hours. If the carpet is still damp after 24 hours it was over-wetted, and the risks are a musty smell, brown marks rising to the surface, and on some carpets rippling as the backing loosens. Open windows, run fans, make extra dry passes and keep foot traffic off until it is dry right through.
Can I use a hired carpet cleaning machine on a rug?
On a small synthetic rug, carefully, yes, though it is better done outside on a clean surface than on a wooden floor that the water can soak into. On wool, viscose, silk, jute, sisal or any hand-knotted rug, no. Those fibres can brown, shrink, bleed or lose their pile with that amount of water, and they need a different method entirely.