Viewing a used hot tub: the complete inspection checklist

Viewing a used hot tub usually takes an hour to an hour and a half, and that time decides whether you take home years of enjoyment or an expensive repair. This checklist walks you through the visit in the order you will actually go through it on site: what to ask the seller for in advance, what to bring, what to check outside, on the shell, behind the service panel and while it is running, and which signs mean it is time to say a polite goodbye. At the end you will find a short checklist to tick off, which you can print and take with you.

What should you ask the seller before the viewing?

The most important request: the hot tub should be filled, switched on and heating for a day or two when you arrive. An empty or cold hot tub will not show whether it leaks, whether it heats up and whether every pump works. If the seller is not willing to do this, that alone tells you something.

• Set temperature. Ask for the heating to be set to the usual bathing temperature (for example 37 or 38 °C), so you can see that the hot tub really holds it.
• No freshly changed water. Water changed just before your visit can hide poor water care. It is fine if the water is a few weeks old, as long as it is well looked after.
• No jets running beforehand. If the pumps start for the first time in front of you, you can see whether deposits or flakes come out of the jets.
• Accessible service panel. Ask for the service panel in the cabinet to be removable, with no furniture, plants or steps in front of it.
• Paperwork ready. Invoice, owner's manual, service records and, if possible, a photo of the rating plate with the serial number sent in advance.
• Daylight. You will see far more in daylight than under artificial light.

What should you bring to the viewing?

A few simple tools let you see much more than the naked eye. Worth packing:

• A torch or head torch. To shine behind the service panel, under the hot tub and into the jets.
• Water test strips (pH and sanitiser). In a minute they show you what state the water is in.
• A simple water thermometer. To compare with the value on the display.
• A phone for photos and video, ideally fully charged.
• Paper towels. Touch the pipe connections and the insulation and you will know straight away whether they are dry.
• A tape measure. Note the size of the hot tub and the narrow points along the delivery route.
• Swimwear and a towel, if you want to try it: that way you feel whether the seats are comfortable and whether the massage suits you.
• This checklist, printed, and a pen. If you can, bring along a knowledgeable friend or a professional too.

What should you check outside, on the cabinet and the base?

Start outside and walk all the way round: the cabinet and the ground under the hot tub reveal a lot about leaks and care. Before anything is switched on, check these:

• Cabinet. Cracks, warping, rot, damp or crumbling parts. A wooden cabinet needs more care, while a plastic or composite cabinet is usually more durable.
• Under and around the hot tub. Damp patches, puddles, wet concrete, limescale lines or rust stains under the hot tub and along the bottom of the cabinet.
• Level and base. Is the hot tub level, or has one corner sunk? A sloping water surface can point to a poor base or a damaged frame.
• Signs of pests. Gnaw marks along the bottom of the cabinet, droppings, nesting material in the gaps.
• Electrical connection. Visual check only: tidy, protected cable routing and a residual current device (RCD) in the supply. Do not touch any electrical parts.

How do you check the shell?

On the shell, cracks and blistering matter most, because they are difficult and expensive to repair, while surface scratches are mostly cosmetic. Hold the torch at a low angle to the surface: that way even small irregularities and hairline cracks stand out.

• Cracks, blisters, networks of hairline cracks. Look especially at the edges of the seats, the step, around the jets and in the corners.
• Fading, stains. Large faded areas can point to prolonged sun exposure or harsh chemical use.
• Firmness. Press down on the seats, the step and the footwell by hand: they should not flex or creak.
• Headrests. Crumbling, sticky or cracked headrests can point to irregular water care. They are cheap to replace, but they are an important signal.
• Waterline. A thick band of limescale or grease at the water level points to infrequent water changes and cleaning.

What should you see behind the service panel?

Most purchases are decided behind the service panel: this is where you see whether the equipment is dry and tidy, or shows signs of leaks, corrosion and makeshift repairs. Let the seller remove the panel, and look inside with a torch while the pumps are running, because many small leaks only appear during operation.

Water and leaks

• Drips, wet or spongy foam insulation, a puddle at the bottom of the hot tub.
• White, crusty deposits (limescale) on pipe connections, unions and pump seals: these are traces of an older leak that has dried out.
• Good to know: water running along the frame and the insulation often shows up some distance from where the real fault is. A damp patch does not always mean the connection directly above it.

Signs of frost damage

If the hot tub stood without power for a long time in winter, or was drained incorrectly, water left in the pipes may have frozen. Frost typically cracks the heater housing, the filter housing, the pump housing and the connections. Look for cracked fittings, pipes with hairline cracks and signs of recent repairs at these points, and ask how the hot tub spent the winter.

Equipment and electronics

• Rust, or green, bluish or whitish powdery corrosion on the pumps, the heater and the connectors.
• Makeshift repairs: insulating tape, glued pipe extensions, clamps that do not belong there.
• Signs of rodents: chewed cables, chewed insulation, nests, droppings, a musty smell.
• A burning smell, browned or discoloured cable insulation around the control box.

How do you test the pumps and jets?

Switch on every pump one by one, at every speed, and listen to the sound, feel the vibration and watch the water coming out of the jets. A steady, deep hum is fine, but grinding, clicking, knocking or a sharp whine can point to a worn bearing or a repair that will soon be due.

• At the first start, watch the water: if flakes, slimy bits or brownish dirt come out of the jets, biofilm (a coating of bacteria and organic dirt) has built up in the pipework. A thorough line flush can deal with it, but it points to neglected water care.
• Every jet should give a strong, even stream. Check for missing, cracked or stuck jets, and that the rotating jets turn evenly.
• Diverter valves and air controls. Turn them all the way: they should move easily and noticeably change the water flow.
• Air blower (if fitted): it should start, and bubbles should come evenly from every outlet.
• Circulation pump (if fitted): it should run quietly and continuously.

How do you check the heater and the temperature?

The surest way to check the heater is that the hot tub has already reached the set temperature when you arrive, and your own thermometer shows roughly the same as the display. That is why the seller should switch it on a day or two in advance: heating is a slow process and typically raises the temperature by only a few degrees per hour, depending on the hot tub and the weather.

• Compare the temperature on the display with your own thermometer. A difference of a degree or two is not a problem, but a large difference can point to a faulty sensor.
• Ask the seller to raise the set temperature by one degree. On most controls a heating indicator appears, and the heater should start.
• Manufacturers typically set the maximum water temperature at 40 °C. If the hot tub is warmer than that, or the display shows overheating, there is a fault.

Control panel and error codes: what should you watch for?

Every button on the control panel should work, the display should be easy to read, and no error code should appear, neither at the start of the visit nor while the pumps are running. Error codes differ between manufacturers and control systems, so if you see anything, photograph it and look it up in the owner's manual.

A single message with a clear explanation (for example a filter cleaning reminder) is no cause for concern. Recurring flow and overheating errors, however, usually signal a more serious repair.

How do you check ozone and UV-C water treatment?

If the hot tub has an ozone generator or a UV-C lamp, check that it works and ask when it was last serviced: these systems reduce the amount of chemicals needed, but if they are faulty, they are only valuable in the listing.

• Ozone. When it works, you typically see a steady stream of tiny, fizzing bubbles from a single outlet, and many units also have an indicator light. Worth knowing: the bubbles only prove that air is flowing, not that the unit is actually producing ozone. Ask when the generator or the injector was last replaced.
• UV-C. On most systems an indicator light or a display message shows its status. Manufacturers typically specify replacing the lamp every one to one and a half years, so ask when it was last changed. Never look into a UV-C lamp.

Lighting, sound system and extras

Try every extra listed in the advert on site, because repairing or replacing them costs extra, and the seller based the price on them.

• Underwater and exterior lighting, every colour and mode.
• Waterfall, fountain, sound system, remote control.
• Wi-Fi module and mobile app: ask the seller to remove the hot tub from their own account at handover, so you can register it.
• Steps, handrail, accessories: are they there, and are they included in the price?

How do you check the cover and the cover lifter?

Lift the cover by its handles: if it is unusually heavy, the foam core has soaked up water. Waterlogged foam cannot be dried out, it loses its insulating ability, and the cover needs replacing. Factor this into the price.

• Outer skin. Tears, cracked or faded vinyl, split seams, a damaged hinge between the two halves.
• Fit. The cover should close well and should not be broken or sagging in the middle. Steam escaping at the edge points to a poor seal.
• Smell and moisture. If the underside of the cover is wet, mouldy or smells musty, the foam has probably soaked up water.
• Fastening. Are the locking straps there and do they work? With children around, this is also a safety issue.
• Cover lifter. Try it: it should move smoothly, with no rusty, loose or broken parts, and the cover should not slip off it.

What do the water and the filter tell you?

The water mirrors how the hot tub has been cared for: it should be clear and colourless, with no strong smell. Cloudy, foaming or greenish water, a musty or strong chlorine smell, or a slippery shell surface point to neglected water care.

• Test strip. For most hot tubs, a pH between 7.2 and 7.8 is typically ideal; the exact range is given in the manufacturer's manual. A value far outside it and zero sanitiser point to irregular care.
• Filter. Ask the seller to take out the filter cartridge. The pleats should be intact, not torn, slimy or thickly coated with limescale.
• Ask how often the water and the filter were changed, and which water care products were used.

Which documents and serial number should you check?

Read the serial number from the rating plate on the hot tub, and compare it with the details on the invoice, the service records and the advert. With many manufacturers the rating plate is in the equipment bay, near the control box; the owner's manual describes exactly where.

• Rating plate. Photograph it: brand, model, serial number, manufacturing details and electrical data (voltage, current). The electrician will need the latter.
• Invoice or other proof of purchase that confirms where it came from.
• Owner's manual, on paper or digital.
• Service records: which repairs and part replacements were done, and by whom.
• Warranty. With many manufacturers the factory warranty applies only to the original owner and ends when ownership changes. If the seller mentions a warranty, check with the manufacturer or dealer whether it can be transferred.

Which signs mean you should walk away?

If you come across any of the following, feel free to say goodbye, or continue only after a thorough professional inspection:

• The seller will not let you see it filled and running, or will not let you remove the service panel.
• Cracks or blistering on the shell, a seat or footwell that flexes.
• An active leak, waterlogged insulation, signs of frost damage on the equipment.
• Burn marks, chewed cables, heavy corrosion in the equipment bay.
• The hot tub does not heat up, or shows a recurring error code.
• The RCD does not trip when tested, or the hot tub often trips it on its own.
• The rating plate is missing or unreadable, or the serial number does not match the paperwork.
• The seller rushes you, asks for a deposit before the viewing, or dodges simple questions.

How do you document the viewing?

Record everything in photos, video and writing, because you will need it for negotiating, for the contract and later for setting up the hot tub. A well-documented viewing gives both sides peace of mind.

• Photos: every side of the hot tub, close-ups of the shell, the space behind the service panel, the rating plate, the top and underside of the cover, the cover lifter, the display.
• Video: each pump starting, with sound, the jets running, the heating indicator on the display.
• Notes: the ticked checklist, the measured temperature and test strip results, the seller's answers, the list of faults found.
• In the contract: brand, model, serial number, list of accessories and known faults. That way there can be no dispute later about what you bought.

Printable checklist

Take this short list with you and tick off the points on site.

Download the checklist (PDF, 1 page)

Before

• Filled, switched on, heating for 1-2 days
• Water not freshly changed, jets not run beforehand
• Service panel accessible, paperwork ready
• With me: torch, test strips, thermometer, phone, paper towels, tape measure

Outside and underneath

• Cabinet intact, no rot, no warping
• No damp patches, puddles or limescale under the hot tub
• The hot tub is level
• No signs of pests

Shell

• No cracks, blisters or hairline cracks
• Seats, step and footwell do not flex
• Headrests intact

Behind the service panel (with pumps running)

• Dry insulation, no drips
• No limescale crust on the connections
• No frost damage (heater, filter housing, pump housing)
• No rust, corrosion or makeshift repairs
• No chewed cables, nests or burning smell

Operation

• Every pump, every speed: steady sound
• No flakes from the jets at start-up
• Every jet strong, rotating jets turn
• Valves, air controls and air blower work
• Reaches set temperature, my own thermometer agrees
• Heater starts when the setting is raised by one degree
• No error code, every button works
• RCD TEST: trips, restarts after RESET
• Ozone / UV-C works, date of last replacement
• Lighting and extras work

Cover and water

• Cover not heavy, not wet, not torn
• Closes well, straps present
• Cover lifter works smoothly
• Water clear, no foam, no strong smell
• pH and sanitiser tested with a strip
• Filter cartridge intact, not slimy

Paperwork and records

• Rating plate photographed, serial number matches paperwork
• Invoice, manual and service records present
• Warranty transferability clarified
• Photos and videos taken
• List of known faults for the contract