Cleaning and Disinfecting Water Tanks in a Condominium

In condominiums fitted with drinking-water storage tanks, periodic cleaning and disinfection are essential to guarantee the hygienic quality of the water supplied to the flats. Water that stagnates in the tanks can foster sediment, biofilm and the growth of microorganisms, including legionella. Maintaining these tanks is a duty of preserving the common parts that falls on the condominium, coordinated by the manager.

Why tanks must be maintained

Tanks serve to guarantee a water reserve and the pressure needed on upper floors, often combined with a booster pump set. The downside is that water remains in them for some time: without maintenance, sludge, scale and organic matter settle on the bottom and walls, degrading water quality and possibly altering its colour, odour and taste. Under unfavourable conditions of temperature and stagnation, tanks become an environment favourable to bacteria.

Legionella is the best-known health risk linked to plumbing systems. It grows in warm, stagnant water and can spread through the inhalation of aerosols, for example from showers. The national guidelines for the prevention and control of legionellosis indicate proper system management as a fundamental preventive measure, and tank cleaning is part of it.

What the work involves

Cleaning and disinfecting a tank is a technical operation to be entrusted to specialised staff. In general it involves emptying the tank, mechanically removing sediment and scale, washing the surfaces, disinfecting with products suitable for contact with drinking water, and rinsing before returning to service. At the end, the sealing and correct closure of the tank are verified.

The aspects to watch during tank management are:

• Intact covers and closures, to prevent the entry of dust, insects and animals
• Ventilation fitted with filters, to avoid contamination from outside
• Internal materials suitable for contact with water intended for human consumption
• No prolonged stagnation and regular water turnover
• Recording of the cleaning and disinfection work carried out

How often to intervene

The frequency depends on the tank's condition, the materials, the ambient temperature and the applicable technical and health guidance. In the absence of a single interval valid for every system, the prudent practice is to schedule checks and cleaning at regular intervals, more frequent where the risk is higher. The legionellosis risk assessment provided for by the guidelines for buildings helps to set the maintenance plan best suited to the individual condominium.

Rather than fixing a generic interval, it is better to rely on the system's real conditions and the technician's opinion, documenting every choice. A well-designed and maintained tank requires fewer extraordinary interventions.

Who is liable in the condominium

Tanks and the common plumbing system fall among the common parts under Article 1117 of the Italian Civil Code. Their maintenance is therefore the condominium's responsibility and their management the manager's, who under Article 1130 oversees the preservation of common parts and compliance with safety requirements. Neglecting tank cleaning, with consequences for owners' health, can expose the manager to liability.

The manager schedules the work, chooses qualified firms, keeps the documentation and informs owners when the supply is temporarily suspended for maintenance. If a concrete health risk emerges, the manager acts promptly, involving the technician and, if necessary, the competent authorities.

Cost allocation

The cost of cleaning and disinfecting common tanks is normally allocated among owners according to the criteria of Articles 1123 and following of the Italian Civil Code. If the tank serves the whole building, allocation is by ownership thousandths (millesimi); if it serves only some units, the cost falls on the owners concerned according to the relevant table. As this is generally recurring ordinary maintenance, the cost is part of the annual budget.

When, instead, extraordinary work becomes necessary, such as replacing or rebuilding the tank, the rules for extraordinary maintenance apply, with a resolution of the owners' meeting under Article 1135 of the Italian Civil Code.

Planning water hygiene and safety

The quality of the supplied water is an aspect of condominium management that directly affects health. Placing tank cleaning in a planned maintenance calendar and keeping the records of the work and the risk assessment makes it possible to demonstrate diligence and to react quickly to anomalies.

With AmministraPro the manager can schedule the tank cleaning and disinfection deadlines, store the work reports and the risk assessment, and notify owners of temporary supply suspensions. The maintenance and communication features are described on /funzioni, with the plans on /prezzi.