Maintaining Water and Plumbing Systems in an Office Building: What You Must Do and Why

Of all the systems in an office building, the water system is the one where neglect exacts the highest price — and usually the quietest. Fire is discovered immediately, an elevator that gets stuck is dealt with the same day, but a slow leak behind a wall, a reservoir that goes undisinfected, or a hot-water system that breeds Legionella bacteria — all of these work beneath the surface, for months and even years, until they erupt as structural damage, mold, or a real health hazard. This article explains, from direct experience in building management, what preventive water maintenance actually involves and why it cannot be skipped.

Why water in particular — the three dangers that hide together

The reason the water system is so dangerous when neglected is that it combines three entirely different kinds of damage in the same infrastructure:

• Health hazard: water is a medium. A reservoir that is not disinfected, or a hot-water system at the wrong temperature, becomes a source of bacteria — including Legionella, which can cause severe illness through inhalation of a contaminated water aerosol.
• Slow structural damage: a small leak does not reveal itself as a puddle. It seeps into concrete, plaster and insulation, corrodes reinforcing steel, and eats away at structural elements for months before anyone sees a stain on the wall.
• Mold and air quality: moisture trapped behind a wall or beneath flooring breeds mold that harms indoor air quality and the health of tenants. It is usually detected first by the smell.

All three share a troubling trait: they are invisible at the early stage — the cheap, fixable one. By the time they become visible, they are already expensive. This is exactly the logic of preventive maintenance — to catch the problem while it is still quiet.

From experience: a building that comes to us after several years without organized maintenance almost always presents a combination of two of the three — usually a hidden leak that led to mold, or a faulty backflow preventer that no one checked for years. The urgent treatment costs many times more than the routine maintenance that was withheld from it.

Drinking-water reservoirs — disinfection, testing and documentation

Many office buildings keep a reservoir of water for drinking and sanitary use — sometimes on the roof, sometimes in the basement — that ensures pressure and continuity of supply. The reservoir is a health weak point: standing water, heat, and the ingress of dust or contaminants can turn it from a source of clean water into a source of contamination.

Legal requirements: the Public Health (Water Supply and Sanitation) regulations and the relevant health regulations require the maintenance of drinking-water reservoirs, including periodic disinfection by a certified party. The Ministry of Health is the central supervisory body. In addition, local water authorities (water corporations) may add requirements on top of the national baseline — it is worth verifying with the relevant body for your area.

Routine maintenance of a drinking-water reservoir includes:

• Checking that the reservoir is sealed and covered — with no ingress of light, dust, birds or insects.
• The integrity of the internal lining and the absence of rust, cracks or notable sediment buildup.
• The soundness of the float valve and overflow protection.
• Performing disinfection by a certified party and documenting the results — the disinfection certificate and water tests are kept in the building file.

Do not treat reservoir disinfection as a technical "annual form". This is the action that stands between the drinking water of dozens or hundreds of people in the building and actual contamination. Insurers and health authorities may demand the certificates in the event of an incident — if you do not know when your reservoir was last disinfected, that is the place to start.

Backflow preventer — the annual test almost everyone forgets

If there is one water system that building owners know least about and forget most — it is the backflow preventer. This is a device installed on the building's water connection to the municipal network, whose job is to prevent reverse flow: water from within the building — which may be contaminated from a fire-suppression system, an irrigation system, a chiller, a boiler or any internal source — must not flow back and contaminate the drinking water in the public network.

The backflow preventer is a crucial health-safety component, and therefore requires an annual fitness test by a certified backflow-preventer inspector. The test verifies that the valves seal properly and that the device indeed prevents reverse flow. This test is not optional — many water corporations require the annual test approval; failure to perform it may lead to enforcement and sanctions in the event of an incident.

Why is the backflow preventer so forgotten?

Because it works "in the background", is not visible to users, and does not alert anyone when it fails. A building owner can go years without knowing that their backflow preventer is faulty — until contamination is discovered, until the water corporation conducts an audit, or until an incident occurs. I have seen buildings whose backflow preventer had not been tested since installation a decade earlier. Once the property owner's attention is drawn to it, they are usually surprised to learn it even exists.

Manage the backflow-preventer test like any other statutory inspection: scheduled in advance, a certified inspector, and the approval kept in the building file.

Legionella and hot-water systems — a real silent danger

Legionella (Legionella pneumophila) is a bacterium that multiplies in standing water within a lukewarm temperature range (mainly 25–50°C), and can cause Legionnaires' disease — a severe pneumonia — when a person inhales a contaminated water aerosol. In an office building, the risk lies mainly in the hot-water system: boilers, long pipe runs, showers that are rarely used, and especially pipe sections where hot water stands for a long time at an inadequate temperature.

The accepted professional principle for prevention: temperature management — keeping hot water above a threshold known to reduce proliferation (usually above 60°C in the boiler) and preventing standing lukewarm water in which the bacterium thrives. Cold water should stay cold along the entire route. Legionella thrives mainly when the two systems "mix" thermally due to poor insulation or pipe proximity.

Preventive maintenance that addresses Legionella includes:

• Temperature control — that the boiler and pipes hold the correct temperature along the entire route, not just at the boiler.
• Flushing water at endpoints that are not in regular use, to prevent prolonged standing — especially important after holidays, summer breaks and lockdowns.
• Identifying and treating dead pipe sections left after renovations, changes of use, or removed connections.
• Maintaining the boiler itself — removing scale and sediment that serve as a medium for bacteria and reduce heating efficiency.

It is important to understand: Legionella is not a theory. Disease outbreaks in office buildings and hotels have been documented around the world, and these outbreaks are almost always linked to poor maintenance of the hot-water system. In Israel, the Ministry of Health publishes guidelines on managing Legionella risk in institutions and public buildings — a responsible building manager is familiar with them.

Boilers — beyond temperature

The boiler is the heart of the hot-water system, and it undergoes continuous wear. Two processes operate within it over time: the buildup of scale and sediment, which reduces efficiency and accelerates failure; and corrosion, which eats away at the tank until it leaks. A failing boiler is not just a hot-water problem — it can release a large amount of water at once and cause immediate damage to an entire floor.

Preventive maintenance for a boiler includes:

• A general fitness check and detection of early signs of corrosion.
• Releasing accumulated sediment and scale.
• Checking the safety valve — the one that prevents dangerous pressure and constitutes a critical line of defense.
• Checking the electrical elements and the integrity of the boiler insulation.

A boiler showing signs of corrosion or a slight drip is an early warning that must not be ignored — it is better to replace it in an orderly plan than after it floods a server room or an archive.

Sewage and drainage — the system that is ignored until it overflows

The sewage and drainage system works by gravity and in silence — until it clogs. Then it immediately becomes the most unpleasant problem in the building: sewage overflow, odor, and damage to floors and walls. In the buildings I have managed, the common blockages originate from fats from kitchenettes, from wipes and waste flushed down toilets, and from sediment that accumulates in the pipes over years.

Preventive maintenance for sewage and drainage:

• Periodic flushing of the main sewage lines (usually with water pressure) to prevent buildup.
• Checking and cleaning the grease separators in kitchenettes — when a grease separator fills up, it sends fat directly into the sewage and floods the line.
• Cleaning gutters, valves and roof drains before the rainy season — a clogged roof drain is a leading cause of flooding on upper floors.
• Checking sewage pumps and sump pits in basements, including checking the backup in case of a power outage.

Planned cleaning of the sewage lines costs far less than an overflow emergency, which sometimes requires evacuating tenants, repairing floors and storing equipment.

Leak detection — catching the damage while it is still small

The slow structural damage described above almost always begins with a small, imperceptible leak. That is why early leak detection is one of the most important tools in water maintenance. The signs you should know how to identify:

• Water consumption that rises without explanation — a water meter that keeps moving when there is no use is a classic red flag.
• Moisture stains, peeling paint or plaster, swelling in drywall.
• A musty smell in enclosed spaces, storerooms, systems cabinets.
• Unexplained drops in water pressure, or unexplained "cold zones" in hot piping.

The meter-check method — simple and powerful

Reading the water meter during hours when there is no activity in the building (night, weekend, holiday) is the most accessible test: if the meter moves and no tap is open — there is a hidden leak. This is a technique I apply in every new building that comes under management — it often reveals a leak no one knew about.

When suspicion arises, there are professional tools for precise detection: acoustic detection that listens for the sound of flow in the pipes; a thermographic survey (thermal camera) that identifies temperature differences in the wall. Both locate the source of the leak without dismantling half a floor. The golden rule: a leak detected in the first week is a small repair; the same leak after six months is structural damage and mold.

Integrating the water system into the annual maintenance plan

None of the actions above is a one-off "project" — they are all periodic inspections at different frequencies, and that is precisely the point. Reservoir disinfection, backflow-preventer testing, temperature control in hot water, drain cleaning, boiler inspection — each has its own frequency. Without a party centralizing the schedule, one of them always "falls between the chairs".

The water system is part of the full set of inspections required under Israeli Standard (SI) 1525 for building maintenance, and therefore it should enter the same documented annual plan as any other system. As with air-conditioning system maintenance, here too the connection between the systems is not incidental: cooling towers, chillers and hot-water systems touch one another, and the Legionella risk crosses both systems. A good maintenance plan sees the full picture. We have consolidated the complete cycle in the annual preventive-maintenance checklist.

The multiplicity of parties — the management challenge that increases risk

The water system of an office building involves various certified parties: a reservoir disinfector, a backflow-preventer inspector, a licensed plumber, a sewage company, a boiler technician. Each comes as needed, and if there is no management party centralizing them all — the inspections will be scattered, postponed, and some will disappear.

Israeli culture tends to act in response to an external demand: when an inspector arrives, when the authority requests an approval, when something is already leaking. But the water system is precisely the domain where this approach fails — because by the time the problem becomes visible, it is already expensive: water contamination, structural damage, mold requiring remediation. Preventive maintenance acts ahead of the external demand, while the problem is still quiet and cheap.

A management party that centralizes the inspection schedule, schedules it in advance, ensures deficiencies are closed and keeps all approvals in one place — turns the water system from a hidden source of risk into a system known to be sound and proven to be so. This is exactly the kind of work centralized by comprehensive property management.

At Domera we build and manage a complete preventive-maintenance program for a property's water systems — reservoir disinfection, backflow-preventer tests, Legionella prevention, sewage and leak detection — with a centralized schedule and approvals. Get a quote for a review of the state of your water system.