Introduction
High season at a holiday rental is not won in July. It is won in April, on the morning somebody opens the plant room with a list in hand and checks, one by one, the fourteen things that can ruin the summer.
The difference between an owner who runs this check and one who does not is invisible in May. It shows up on the first full-occupancy weekend of August, when the filter stops coping and the pool goes cloudy on a changeover day. At that moment, the cost of not having checked the filter pressure in April turns into a written review on a public platform that keeps costing you bookings two years later.
This is the checklist we use on the holiday-rental pools we maintain in Lisbon and on the South Bank. It is ordered the way the checks should actually be run — because some only make sense after others — and each point says what to look for and what to do if it is wrong.
Before You Start: Two Questions
Before touching any equipment, answer two questions in writing. They determine everything else.
How many guests will you take, and at what rhythm? Preparing a house that takes four people a fortnight is not the same as preparing one that takes twelve rotating weekly. Bather load — not pool volume — is what sizes the filtration, the disinfectant demand and the visit frequency.
Which day of the week do your stays begin? If changeovers are on Saturday, all summer maintenance has to happen before Saturday. A visit booked for Monday is no use.
Write both answers down. We use them at points 9 and 13.
Stage 1: Structure and Safety (points 1 to 4)
1. Lining and coping
Drop the level enough to see the waterline and walk the perimeter. Look for: liner lifting or blistering, loose tiles, cracked gelcoat, sharp edges on the coping.
A loose tile in the shallow end is a cut on a child's foot, and exactly the sort of detail that ends up in a review. Fixing it in April costs a morning; fixing it in August means closing the pool at full occupancy.
2. Ladders, handrails and fixings
Shake every ladder and handrail hard. Any play means the fixing is working loose — usually corrosion in the chemical anchors, and faster in salt-air locations.
3. Fence, gate and barriers
If there is a fence, check the latch and the gate's self-closing action. If there is none, this is the moment to decide: a house that takes families with children and has no barrier at all is an exposure a line in the house manual does not fix.
4. Signage and pool rules
Depth marked, rules posted, and in the languages your guests read. A laminated A4 by the poolside with hours, adult supervision of children, no glass, and a note that use is at the user's own risk. It costs two euros and it is the document that shows you set rules and communicated them.
💡 Dica Profissional
Photograph the posted notice, with a date. If there is ever an argument about what was or was not communicated to guests, a dated photograph is worth more than your recollection.
Stage 2: Equipment (points 5 to 9)
5. Pump: start-up, noise and flow
Start the pump and listen for a full minute. A high-pitched whine is a bearing; a hollow, irregular sound is cavitation, usually air on the suction side or a blocked basket.
| Symptom | Likely cause | Action |
|---|---|---|
| Constant high-pitched whine | Bearing at end of life | Replace now, not in July |
| Irregular, "gulping" sound | Air on the suction side | Check lid seal and water level |
| Pump will not prime | Lost seal or suction leak | Diagnose before insisting |
| Runs excessively hot | Motor or start capacitor | Do not leave it running |
6. Filter: reference pressure and sand condition
Note the pressure with the filter clean, immediately after a backwash. It is the single most useful number on this checklist, because it is the reference every summer reading gets compared against.
Filter sand has a service life. If pressure climbs quickly after every backwash, if the water never really clears, or if the sand is more than five to seven years old, replace it now. Replacing sand with guests in the house means a pool out of service for hours.
7. Multiport valve and circuit
Run the valve through every position and check for leaks in each. A valve passing to waste while set to filter is a continuous water loss you only discover on the bill.
8. Electrical panel and RCD
Test the RCD with its test button. Check the terminals for corrosion — in coastal locations it is the first thing to fail. The panel in the plant room of a pool that takes the public is no place for improvisation.
9. Sizing against the number of beds
Here we use your first written answer. With the pump's flow rate and the pool volume, work out the turnover time — how long the whole volume takes to pass through the filter. Then ask: does this turnover time cope with twelve people using the pool every day in August?
If the answer is no, or if you do not know, that is exactly what an on-site technical diagnosis answers in writing. A pool built for family use frequently runs right at its limit once it goes into tourist service, and this is almost always why.
Stage 3: Water (points 10 to 12)
10. Balance, in the right order
The order is not optional:
- Total alkalinity first (80 to 120 mg/L). It is the pH's brake. Setting the pH with the alkalinity wrong is wasted work.
- pH next (7.2 to 7.6, ideally 7.2 to 7.4).
- Disinfectant last (free chlorine 1 to 3 mg/L; on a pool in tourist use, work in the upper third).
11. Cyanuric acid
If you use stabilised chlorine, measure it. Above 75 mg/L the chlorine stops disinfecting even though it is present — the classic cause of a pool that "has chlorine" and goes green anyway. The only real correction is dilution with fresh water, and that is far easier in April than in August.
12. Calcium hardness
200 to 400 mg/L. Relevant in hard-water areas and decisive in keeping limescale out of the filter, off the walls and out of heat exchangers. We cover the consequences in Removing Limescale from Pool Walls.
Stage 4: Organisation (points 13 and 14)
13. Visit calendar against booking calendar
Your second written answer. Put the booking calendar next to the maintenance calendar and check that every guest arrival is preceded by a visit, not followed by one.
In high season, the weekly visit is the realistic minimum on a holiday rental. Houses with back-to-back stays need more.
14. A written record, starting today
Start the log at opening, not the first time something goes wrong. Date, time, pH, free chlorine, combined chlorine, temperature, number of bathers, product applied.
We have a free printable water-testing log template: one A4 sheet to pin up in the plant room. After one season, those sheets are the history that lets you treat causes instead of symptoms — and the proof the pool was being maintained, if a complaint or a claim comes up.
The Checklist in Short
| # | Check | If it is wrong |
|---|---|---|
| 1 | Lining and coping | Repair before the first booking |
| 2 | Ladders and handrails | Refix or replace |
| 3 | Fence and gate | Decide and budget |
| 4 | Signage and posted rules | Print and post today |
| 5 | Pump: noise and start-up | Diagnose before June |
| 6 | Reference pressure and filter sand | Replace sand out of season |
| 7 | Multiport valve | Seals or replacement |
| 8 | Panel and RCD | Electrician |
| 9 | Turnover time vs number of beds | Technical diagnosis |
| 10 | Alkalinity, pH, disinfectant | Correct in that order |
| 11 | Cyanuric acid | Dilute with fresh water |
| 12 | Calcium hardness | Scale treatment |
| 13 | A visit before every arrival | Reschedule the calendar |
| 14 | Written log started | Print the template |
Common Mistakes
Opening the pool in June. Opening in April gives you two months of slack to find problems. Opening in June means finding them with guests in the house.
Shocking the pool before fixing the pH. With the pH out, most of the product does nothing. Alkalinity first, then pH, then disinfection.
Not writing down the filter's reference pressure. Without that number, the filter pressure in August tells you nothing.
Assuming what worked last year works this year. If you added beds or switched platform and occupancy rose, the pool has changed category.
Leaving the pool abandoned over winter to save money. Recovering a green pool in April costs more than the winter maintenance that would have prevented it.
Frequently Asked Questions
When should I open a holiday-rental pool?
In April, or at the latest the start of May, even if the first booking is in June. The slack exists to deal with whatever the checklist finds — replacing sand, fixing a tile, ordering a pump — without calendar pressure and without guests in the house.
How long does this check take?
The check itself, two to three hours on a normal pool. What takes time is what it finds. That is why it is done in April.
Do I need a professional for this?
Most points are within reach of an attentive owner. Three are not: the turnover-time calculation against the number of beds (point 9), work in the electrical panel (point 8), and replacing filter sand (point 6). The first two on competence, the third on sheer physical work.
My pool was built for the family. Can it take guests?
That is the whole question behind point 9, and it cannot be answered remotely. It depends on the circulation flow rate, the filter's capacity and the number of beds. An on-site diagnosis gives you the answer in writing before you accept the first booking.
What do I do if I find a serious problem in April?
Quote it and fix it. That is precisely why the check happens now: in April, a filter to replace is a planned expense. In August, it is a closed pool with guests in the house and a three-star review.
Conclusion
Fourteen checks, one April morning, and high season stops depending on luck.
Key points to remember:
- Bather load, not pool volume, is what sizes everything.
- Write down the clean-filter pressure. It is the most useful number on the list.
- Correct the water in the right order: alkalinity, pH, disinfectant.
- Start the written log at opening, not at the first problem.
- Every guest arrival should be preceded by a visit, not followed by one.
If you would rather this check was run and documented by people who do it every day, the on-site technical diagnosis costs €45, deductible from your first month under contract. We work in Lisbon and on the South Bank.
