Drain and Refill, or Treat the Water You've Got? The Breakpoint: Questions Answered
Many owners get the drain-or-treat decision wrong by focusing on the immediate symptom—like cloudiness or a strange smell—instead of the underlying cause, typically a build-up of total dissolved solids or biofilm. This hub answers the questions that target the root of the problem, helping you decide whether to drain and refill or continue treating your water.
Recognising chemically exhausted water
When your inflatable hot tub water stays cloudy despite adding chemicals, you’re likely dealing with water saturated with dissolved solids. At this point, treatments become ineffective. Draining and refilling is often the better option than repeatedly adding chemicals that just react with the existing residue. Full details are in our guide, How Often Should You Change the Water in an Inflatable Hot Tub? It Depends on Three Things .
Draining a Lay-Z-Spa
You can drain a Lay-Z-Spa without a pump using a hose. Common methods include using a dedicated drain adaptor that connects to the spa’s valve or setting up a DIY siphon. The adaptor typically provides a more controlled flow, while the siphon method can be trickier to manage. Learn the steps in our guide, Draining a Lay-Z-Spa Without a Pump: The Garden Hose Method and Where the Water Should Go .
The importance of flushing pipes
Draining the water alone doesn’t remove the slimy biofilm coating the inside of your pipes. This biofilm can be why water turns cloudy or develops a smell again soon after you refill. Using a flush product cleans the pipework and jets before fresh water goes in. We examine whether it’s worth it in our guide, Cleaning Hot Tub Pipes Before a Refill: Is a Flush Product Worth It? .
Getting the chemical sequence right
A common error is adding sanitiser first. If the water’s pH and alkalinity aren’t balanced, the sanitiser will be used up too quickly. Start by creating a stable base with pH and alkalinity adjusters, then add your sanitiser. The full sequence is in Refilling a Hot Tub: What to Add First, and in What Order .
Timing your water change
Rather than just relying on the manufacturer’s maximum interval, change the water sooner if it looks or smells off. Your actual usage and local water quality can mean you’ll need to refill more often than the calendar suggests. The key factors are explained in How Often Should You Change the Water in an Inflatable Hot Tub? It Depends on Three Things .
Safe drainage practices
Be careful where you direct the hose. Chlorinated water shouldn’t flow into watercourses or a neighbour’s property. The safer route is a foul drain (the kind your kitchen or bathroom drains into), not a surface-water drain. Letting the sanitiser level fall for a few days first reduces the impact; if you’re unsure which drain is which, your water company can tell you. Guidance is in Draining a Lay-Z-Spa Without a Pump: The Garden Hose Method and Where the Water Should Go .
Why your chemicals eventually fail
Over time, chemicals can seem to stop working because the water becomes saturated with Total Dissolved Solids (TDS). This includes minerals and spent chemical residue. In this saturated state, new treatments struggle to react properly with contaminants. This breakpoint is the focus of our guide, Drain and Refill, or Treat the Water You’ve Got? The Breakpoint .
Comparing drainage techniques
The drain adaptor fits the spa’s valve for a controlled, gravity-fed flow. The siphon method is a DIY technique where you start a flow by submerging a filled hose, but it offers less control over the process. Compare them in Draining a Lay-Z-Spa Without a Pump: The Garden Hose Method and Where the Water Should Go .
The limits of shocking cloudy water
If the water is saturated with dissolved solids, adding more shock is often a waste. The chemicals can’t react correctly, so it won’t clear the cloudiness. Shocking water that’s past its breakpoint is ineffective. This is covered in Drain and Refill, or Treat the Water You’ve Got? The Breakpoint .
Addressing mould and odour sources
Mould and bacteria can lurk inside pipework, out of reach of normal cleaning. This leads to a musty smell that comes back after refilling. Flushing the pipes before adding new water removes this biofilm. Find out how in Cleaning Hot Tub Pipes Before a Refill: Is a Flush Product Worth It? .
Diagnosing smells in new water
A sweet or off smell in freshly filled water can signal bacteria or organic matter, often hiding in the plumbing. Even after adding chemicals, the smell may persist if the source is trapped inside the pipes. This is explored in Cleaning Hot Tub Pipes Before a Refill: Is a Flush Product Worth It? .
When clear water still smells bad
If your water looks clear but smells bad, the pipework is the likely culprit. Biofilm can harbour bacteria that survive standard sanitiser levels. Flushing the system before a refill is the best way to eliminate this odour source. See Cleaning Hot Tub Pipes Before a Refill: Is a Flush Product Worth It? .
The question of whether to drain or treat your hot tub water recurs on a predictable schedule. For a clear strategy that helps you anticipate this decision rather than just reacting to problems, our water-change frequency guide is the place to start. For the complete picture, begin with Drain and Refill, or Treat the Water You’ve Got? The Breakpoint .