How to fill a hot tub with a bucket or watering can (and avoid air locks!)

When a hosepipe ban is in full swing, keeping your hot tub filled can feel like an impossible task. However, under standard Temporary Use Bans, filling a spa using a hand-held bucket is legally permitted. While carrying several hundred litres of water in buckets to fill your hot tub is undoubtedly a workout, it is a completely viable way to keep your spa in use. To save your back, and your hot tub’s plumbing, here is the ultimate guide to successfully bucket-filling your spa.

Get a clean bucket or watering can

Before you grab any old plastic bucket from the garage, stop! The absolute golden rule of bucket-filling is that the bucket must be clean, and we mean really clean.

Never use a household bucket that has previously held car wash shampoo, window cleaner, mop detergents, or garden weedkiller. Even a microscopic trace of leftover soap or surfactant will turn your hot tub into a giant bubble bath the second you turn the massage jets on.

Ideally, buy a brand-new, heavy-duty builder’s bucket or a clean food-grade container. Give it a thorough rinse with clean tap water before you start.

Take your time: Fill in stages

You don’t have to tackle the entire fill in one session. It is completely fine to fill your hot tub in stages over a couple of days, carrying a few buckets whenever you have a spare moment. If you need to take a break, simply put the hot tub cover back on to keep out garden debris, protect the dry acrylic shell from UV rays, and keep the water clean.

The golden rule here is never to power your spa on until the water level has fully reached the recommended fill line. Running the pumps while dry or half-empty will instantly burn out your heater and damage your filtration system. Just be mindful not to let the filling process drag on for too long; untreated water sitting stagnant in a warm spa will begin to grow bacteria and algae, making your eventual chemical startup much harder.

How to avoid air locks when filling with a bucket

The biggest technical challenge with bucket-filling is avoiding an air lock.

When you fill a hot tub with a hose, the standard practice is to shove the hose directly down the empty filter housing. This forces water through the internal pipework and heater first, pushing the air out of the bottom jets as the tub fills.

If you just dump buckets of water straight into the main seating area of the spa, the water will rise around the plumbing, trapping a large bubble of air inside the pumps and heater. When you turn the hot tub on, the pump will spin but won’t be able to move water, resulting in an “FLO” or “DRY” error code.

How to prevent this with a bucket:

• Prime the pipework first: For your very first 4 to 5 buckets of water, do not dump them into the footwell. Instead, carefully pour them directly down the filter housing (the standpipe). You may want to use a large, clean funnel to make this easier without spilling.
• Fill the rest: Once you have primed the internal plumbing and the bottom of the spa is well-covered, you can freely pour the remaining buckets straight into the main body of the tub.
• Use a pump: If you do get an air lock and you have a submersible pump, once filled, simply place the end of the pump’s hose straight down into the filter housing and the pump in the footwell and use this to push water into the pipework forcing any air out the jets.

Work smarter: The “Trolley & Pump” hack

Let’s be honest: carrying 10-litre buckets back and forth across your garden fifty times is a recipe for a bad back. If lifting heavy buckets is too demanding, you can set up your own water-delivery station using a few simple tools:

• The Mobile Station: Place a large, clean plastic bin or a couple of large buckets onto a garden trolley, sack truck, or wheelbarrow.
• The Setup: Wheel your mobile water station to your outdoor tap, fill the containers, and wheel them over to the side of your spa.
• The Lift: Instead of lifting and pouring, drop a small submersible pump (with a short piece of garden hose attached) straight into the bucket on your trolley. Turn the pump on, and let it lift the water up and into the spa for you!

Another advantage of using a pump is you can put the hose into the filter housing to push water into your pipework first to reduce the risk of getting an airlock.

The final splash

Filling a hot tub by hand takes patience, but it can be done and is an effective way to keep your hot tub running during a hose pope ban. Just remember to take your time, keep your equipment clean, and always fill through the filter pipework first.

If it all sounds like too much heavy lifting, remember that you can always get in touch. We often have business exemptions during water restrictions so one of our technicians may be able to come out to you and perform a flush, drain, and refill service to keep your hot tub fully operational.