How PoolComply's Intelligent PWTAG Traffic Light System Protects Your Pool — Automatically

When a pool operator submits a water test reading in PoolComply, something happens in the background that most software simply doesn't do: the system doesn't just store the number. It evaluates it — automatically, instantly, against the correct thresholds for that specific pool type — and assigns a green, amber, red, or grey status that propagates across the entire platform in real time.

That's the traffic light system. And it's smarter than it might first appear.

1. What Is the PWTAG Traffic Light System?

The PWTAG (Pool Water Treatment Advisory Group) traffic light system is a colour-coded water quality framework that gives pool operators a clear, standardised way to assess whether their pool is within safe operating parameters — and what action to take if it isn't.

Rather than requiring operators to mentally compare raw numbers against reference charts every time they log a test, the traffic light gives an immediate, unambiguous verdict. Green means everything is fine. Amber means investigate and correct. Red means close.

PoolComply implements this framework digitally — so every reading you log is assessed the moment it's submitted. There's no chart to consult, no manual lookup, no chance of misinterpreting a threshold. The system does that work for you, every single time.

2. The Four Traffic Light States

Each state comes with a clear instruction — not just a colour. Operators always know what the status means and what they're expected to do next. And because the assessment runs the moment a test is saved, the status visible on screen is always current — never a day old, never estimated.

3. The Intelligent Part: Pool Type Profiles

Here's where PoolComply's traffic light system becomes genuinely smart: it doesn't apply a single set of thresholds to every pool. It applies the correct thresholds for your specific pool type.

A learner pool, a hydrotherapy pool, an outdoor lido, and a spa all require different water quality parameters. A spa running correctly at 4–5 mg/L free chlorine is perfectly normal. A standard indoor pool at 4 mg/L free chlorine would be flagged immediately. PoolComply knows the difference — because when a pool is set up, a profile is assigned, and every subsequent water test is evaluated against the targets that actually apply to that facility.

This matters because the consequences of applying the wrong profile are significant. A standard indoor pool runs at 2.0–2.5 mg/L free chlorine — apply those thresholds to a spa operating correctly at 4.0 mg/L and the system flags it red. Apply spa thresholds to a standard pool and dangerously low chlorine levels look acceptable. PoolComply's per-pool profile system assigns the right targets from the outset, so every evaluation is made against the standard that actually applies to that facility.

4. What Gets Assessed on Every Test

When you submit a water test, PoolComply evaluates every recorded parameter against the correct threshold for that pool type. A single test can trigger status updates across multiple parameters simultaneously — and the overall pool status reflects the worst individual parameter.

Parameter	Green (Ideal)	Amber (Action)	Red (Close)
pH	7.2 – 7.4	7.0 – 7.8	< 7.0 or > 7.8
Free Chlorine	2.0 – 2.5 mg/L	1.0 – 3.0 mg/L	< 1.0 or > 3.0 mg/L
Combined Chlorine	< 0.5 mg/L & < ½ FC	≥ 0.5 mg/L, or > ½ FC, or > 1.0 mg/L	—
Temperature	≤ 30°C	> 30°C	≥ 40°C
Bather Load	Within capacity	Approaching limit	Exceeds PWTAG max

Values above apply to a standard indoor swimming pool operating at pH 7.2–7.4 with no secondary disinfection. Free chlorine targets differ significantly by pool type — see below. Combined chlorine does not have a red/close threshold — any level above 0.5 mg/L or more than half the free chlorine reading triggers amber and requires investigation, but pool closure is a judgement call based on whether the problem can be resolved quickly.

Why Free Chlorine Targets Vary So Much By Pool Type

Free chlorine is the parameter that changes most dramatically depending on what kind of pool you're running — and applying the wrong target is one of the most common mistakes in pool chemistry. The reason comes down to how chlorine actually works: at lower pH, a higher proportion of free chlorine exists as hypochlorous acid (HOCl), the active disinfectant form. At higher pH, more converts to the far less effective hypochlorite ion. Pool type also determines how quickly chlorine is consumed and how much contamination load the water carries.

The reason UV-assisted pools at low pH can operate at such a low free chlorine level is precisely because at pH 7.0–7.2, a much higher fraction of that chlorine is in the active HOCl form — combined with UV providing a second line of pathogen kill, the effective disinfection power is maintained at far lower FC readings. Running a standard pool at 0.75 mg/L would be dangerous; at the right pH with UV, it can be compliant.

Cyanuric acid (stabiliser) is added to outdoor pools to protect chlorine from UV degradation by sunlight. The trade-off is that it binds chlorine, reducing the proportion available as HOCl. A pool using cyanuric acid must maintain significantly higher free chlorine to deliver the same effective disinfection — which is why outdoor stabilised pools run at FC levels that would look dangerously high in an indoor pool.

Each parameter's status is assessed independently and displayed separately within the system — so you can see at a glance that pH is green, free chlorine is amber, and combined chlorine is fine, rather than just seeing an overall amber and wondering why.

5. Smart Bather Load Logic

Bather load — how many people are in the pool at any one time — has a direct effect on water quality. More bathers means more contamination, more chlorine demand, and greater risk of combined chlorine build-up. Published pool water guidance defines maximum bather numbers based on pool surface area and water depth.

PoolComply monitors bather load as part of every water test entry, and the traffic light applies automatically. But the system is intelligent enough to know that bather capacity rules are not the same for every pool type.

For swimming pools, the system uses a two-threshold approach:

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  Amber: bather count exceeds your facility's configured maximum — investigate and manage entry to the pool.
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  Red: bather count exceeds the absolute maximum derived from surface area — requires immediate action.

This prevents a problem that a naïve implementation would create: for a small spa with a surface area of 3m², the surface area formula gives a maximum of around one bather — which would flag almost every normal spa session as a red close alert. PoolComply's bather logic is built to avoid these false positives while still enforcing the relevant limits correctly.

6. Temperature Rules — Different for Every Pool Type

Water temperature is assessed differently depending on what type of pool or spa you're operating. This makes sense — a spa running at 38°C is perfectly normal and safe; a learner pool at 38°C is not.

PoolComply applies separate temperature thresholds per pool profile:

The 40°C universal red threshold reflects PWTAG and HSE guidance that water above 40°C poses a genuine risk of scalding and cardiac stress, and no pool should operate above this temperature under any circumstances.

7. The Retest Timer — When Green Turns Amber Over Time

Here's a behaviour that sets PoolComply apart from simpler logbook-replacement tools: a pool can be green after its 9am test, and then automatically turn amber by 11:15am — even though no new readings have been logged.

This happens because PoolComply tracks how long ago the last test was submitted. Under PWTAG guidance, pools should be tested at a minimum every two hours during operating hours. Once two hours have passed without a new test, the pool is technically overdue for monitoring — and PoolComply flags this with an amber "Retest Due" status.

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  The two-hour clock only runs during your facility's configured operating hours — no false alarms at 3am or before the pool opens.
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  The retest badge shows exactly how overdue the test is — e.g. "Overdue 1h 14m" — so staff know at a glance how urgently a test is needed.
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  KPI counters on the Manager Dashboard update immediately — a pool overdue for testing is counted as an action item, not as ideal.
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  The moment a new passing test is submitted, the pool returns to green and the timer resets automatically.

8. Saunas and Steam Rooms — Temperature Monitoring Built In

The traffic light system isn't limited to pool water chemistry. PoolComply extends it to saunas and steam rooms, monitoring temperature against each unit's configured safe operating range.

Each sauna or steam room has a manager-configured minimum and maximum temperature. The system then applies the same three-state logic:

Too cold and too hot are treated as different severity levels. A sauna that hasn't warmed up yet is an operational inconvenience (amber); a sauna running dangerously hot is a safety issue (red). The system distinguishes between them automatically, and the KPI counters on the Manager Dashboard track them accordingly.

9. Where the Traffic Light Appears Across PoolComply

The traffic light status isn't buried in a single screen — it propagates across the entire platform so that anyone who needs the information has it, wherever they happen to be working.

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  Manager Dashboard: KPI counts of green / amber / red facilities at the top of the page, plus a colour-coded card for every pool and sauna, updated in real time.
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  PPO (Operator) Dashboard: Facility cards with colour borders reflecting current quality status, so the on-duty operator sees the full picture the moment they log in.
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  Pools & Saunas pages: Individual pool and sauna listing pages show status on every card, plus a colour-coded history table for the last ten readings.
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  Compliance Centre: The compliance overview shows status trends over time, making it straightforward to identify a pool that regularly drifts into amber before the end of the day.
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  Water test history table: Every logged test shows its traffic light status inline — so when a manager reviews the week's records, the colour tells the story without reading every number.

The result is that a manager can walk into the building, open PoolComply on their phone, and know the status of every pool and sauna on site within a few seconds — without asking a single question or opening a logbook. And a pool operator on the poolside has the same information on their device the moment they log a test.