Safe sanitary pipes with a minimum of disinfection products

Keeping sanitary pipes germ-free. Why?

The water supplied by the water supplier is in principle always of good quality. However, drinking water companies cannot guarantee the quality at the tapping point (tap/shower), because they have no impact/control over what happens in the pipes of your building.

What to watch for to limit the growth of disease-causing germs?

Water must not stand still in the pipes for the following 2 reasons:

Water that stagnates (or flows slowly) in the pipes for several days absorbs substances that originate from them. This may involve lead and – depending on the composition and hardness of the water – also iron, zinc or copper. These inorganic deposits cause poorer water quality and reduce the efficiency of the disinfection products.

With stagnant water, a biofilm forms more quickly on the inner wall of the pipes, in which bacteria develop optimally. This biofilm also protects bacteria against heat and disinfectant.

Solution: flush the pipes and tapping points sufficiently. Flushing is not always enough to completely remove the core of the problem (=biofilm), but with the addition of suitable disinfection products, it can be.

Water temperatures must be properly monitored:

Bacteria like moisture and moderate temperatures. Water pipes are therefore the ideal place for the growth of bacteria and other organisms.

Example: the optimal temperature for the growth of E-coli is 37°C. Under these optimal conditions, there is a division every 20 minutes, which means that after half a day, from 1 original germ, approximately 70 billion bacteria are formed.

For Legionella, the optimal growth temperature lies between 35 and 40 °C. Under optimal conditions, legionella colonies grow from 100 cfu / L within 48 hours to the dangerous concentration of 10,000 cfu / L and more. The germ grows in water with a temperature between 20 and 50 °C. Below 20 °C the germ does not multiply and above 55 °C it dies off.

Solution: To control legionella it is advisable to always keep the temperature in cold water pipes below 20°C and to set the temperature in the hot water pipes to at least 55°C (or even better to 60°C). If the desired temperatures cannot be achieved, alternative control measures (heat shock and/or chemical disinfection) must be applied.

Limiting pipe complexity

There are often extensions to existing buildings and therefore also to existing sanitary networks. These extensions cause a changing flow pattern in the pipes.

These changes often result in different pressures and flow velocities, causing:

Water to flow more slowly or even come to a complete standstill (see point 1)

Water pressure becomes more irregular and the water therefore has a different impact (friction) on the pipe materials. These different pressures lead to deposits on the one hand or to corrosion on the other.

Modifications to pipe networks often lead to errors that are only noticed much later when something goes 'suddenly' seriously wrong with the water quality. Common errors are unwanted cross-connections and interconnections. Cross-connections between water from different sources or also between drinking water and non-drinkable water can, among other things, introduce Legionella into the drinking water system.

Solutions: Keep the building plans and especially the plans of the sanitary installations well maintained. Have modifications to sanitary systems properly documented by your sanitary installer.

Monitoring residual disinfectant effectiveness

The use of an additional disinfectant in the sanitary installations often creates a false sense of security. On the one hand, there are few products that legally meet all standards (PT5 registration + approval as an alternative control measure), on the other hand, there are few products that provide sufficient protection to the end of the pipe (tapping point).

Solutions: Request the legally required documentation regarding your disinfectant used from your supplier and measure the residue of the disinfectant used. This gives a good indication of the effective killing of unwanted micro-organisms. These measurements can be offered as a do-it-yourself kit or as a service or as continuous in-line measurement, by your supplier/partner for water treatment.

Safe sanitary pipes with minimal disinfection products