Running a pool: the real monthly cost

Almost everybody asks what a pool costs to build and almost nobody asks what it costs to keep. That is the wrong way round: building is paid once and running is paid every month for twenty years.

This article works that number out from where it can be worked out: the published water and electricity tariff schedules, which are public, dated, and written by nobody with an interest in selling you anything. And it keeps what has a public price clearly apart from what does not, because rolling it all into one figure is exactly how you lose track of where the money goes.

What does have a public price

Two things — pumping and water — and between them they are usually half the monthly spend. The pumping hours are not invented: for the pool of a residential development the rule requires a full turnover every 4 to 6 hours, two to four times a day, with 8 to 24 hours of daily circulation. I take the floor of that band. With a 1 HP pump — 0.75 kW — working eight hours a day, that comes to 180 kWh a month.

On that alone, the reference pool is already running at around $187,000 a month in Bogotá before a single gram of chemical and before paying anyone. That is the floor, and it is a floor you cannot negotiate with a supplier, because you are not paying it to a supplier.

What has no public price, and why

Here is the other half of the spend, and here this article stops dead: there is no official or trade price list in Colombia for pool chemicals, for laboratory analysis or for maintenance labour. Publishing a figure would mean copying a supplier and presenting it as data.

• —Chemicals. Disinfectant, pH corrector, algaecide, flocculant and stabiliser. Consumption depends on temperature, use, sunlight and the quality of the fill water; two identical pools in two different climates spend very differently.
• —Laboratory analysis. It is compulsory and it is monthly, plus an annual analysis. It is not optional, and a strip test kit does not replace it.
• —Labour. Sweeping, brushing, emptying strainer baskets, backwashing and daily monitoring. In-house or contracted out.
• —Spares and consumables. Filter sand or cartridges, pump seals and bearings, the cell if the system runs on salt, and replacement drain covers.

What the rules require, and how often

These frequencies are the part of the rules most often breached, and the part an inspector checks in two minutes:

The lifeguard: where money is overspent and underspent

In a community of owners this is the largest line in the running cost, and it is where most money is overspent. The rule, verified against the articles themselves, is that a residential development needs a certified lifeguard in four situations only: at weekends, in school holidays, at events involving under-14s, and whenever more than ten children are present at once. Not Monday to Friday by default.

The four things nobody budgets for

1. 1Testing the vacuum release system. It is the safety device most likely to fail silently, because it depends on calibration and on nobody having bypassed it.
2. 2Replacing anti-entrapment covers. They break, they get stolen and they degrade under chlorine and sunlight. A missing grating is not a cosmetic defect: it reopens the risk in full.
3. 3Draining, and above all the discharge. Draining the pool costs the water needed to fill it again — $373,608 in Bogotá, stratum 4 — and with no sewer connection the discharge is an environmental permit matter before it is a maintenance decision.
4. 4Renewing the waterproofing and the finish. They have a service life. A maintenance budget setting nothing aside for this is pushing the bill forward, not saving.

How to bring the cost down without breaching anything

• —Cover the water surface. It is the only measure that cuts top-up water, heating energy and chemical use all at once, because less new water means less imbalance.
• —Change the pump before you change the hours. In a pump, flow is proportional to speed and power to the cube of speed: running at half speed for twice as long moves the same volume on a quarter of the energy.
• —Check the head loss. A dirty filter, undersized pipework or a blocked strainer basket make the pump work harder to move the same water. You pay for it on the bill every day.
• —Control pH before chlorine. With pH out of range the disinfectant loses effectiveness and more product is consumed for the same result.
• —Match the lifeguard to the calendar the law sets, not a day more and not a day less. It is where many communities overspend while breaching something else.

How to read a maintenance contract

1. 1How many visits a month, and of how many hours?
2. 2Are chemicals included or billed separately? Under what sanitary registration?
3. 3Does it include the monthly and the annual laboratory analysis, and at which laboratory?
4. 4Who keeps the log book, and where does it live?
5. 5Who posts the results on the noticeboard each month?
6. 6What happens if an analysis comes back out of range? Who bears the correction?
7. 7Does it include testing the safety devices, and how often?

The sixth question is what separates a maintenance contract from a cleaning visit. And if the pool belongs to a community of owners, the conversation does not end at the contract: it ends at the general meeting, and that conversation — with the building manager on the hook — is in what Ley 1209 really requires.

The person who leads this line of work at the practice brings fifteen years of designing hydraulic systems and bodies of water, and what that time teaches about maintenance is uncomfortable and simple: almost the whole monthly cost of a pool was settled at design stage. Pipe diameter, distance to the plant room, filter size and orientation decide what you will pay every month for twenty years. After that you are only administering what has already been decided.