Professionals’ forum Water quality Improving water quality

Improving water quality


As part of its activities to improve the quality of water produced and distributed CDE strives to strengthen disinfection of water as it comes out of production units and within the distribution networks by raising the dose in the networks to 0.5 mg/l.
Disinfection is the final stage of water treatment. It ensures the microbiological quality of water. On leaving the production unit, there is the need to protect water during its transport to the user. Protection is ensured by maintaining a small quantity of disinfectant in the water designed to combat any bacterial pollution that could happen in the distribution network.
On large distribution networks (cases of Douala and Yaoundé), there are chlorination relay stations to avoid overdosage of disinfectant at the exit of the treatment site while ensuring quality at the extraction point.

•    Cleaning and disinfection of storage infrastructure

CDE has established an action plan for cleaning and disinfection of all water storage structures in all the Regional Directorates This action plan that took off in 2008 and will continue with a minimum frequency of once per year.

At the regulatory level, cleaning and disinfection of tanks are a statutory requirement which aims at:

• Maintaining water quality and contributing to its improvement
• Reducing the dose of Calcium hypochlorite (HTH) used for disinfecting water
• Contributing to better asset management.
• Limiting the risk of contamination.
• Respecting the rules

In accordance with regulations, tanks supplying networks and facilities must be emptied, cleaned, rinsed and disinfected at least once a year. Regularly washing tank makes cleaning easier, therefore faster and hence ensures regular monitoring of works.

These actions have enabled us to:
•    Eliminate the number of inadequacies in the quality of water supplied
•    Strengthen the safety of production and water distribution systems in the centres,
•    Optimize the use of treatment products.


•    Turbid or coloured water

Water from your tap may occasionally be turbid or coloured; this does not mean that the water from the mains is undrinkable. This may be due to a problem in the distribution system or in the pipes inside your home. It may also be as a result of dissolved iron from the walls of the pipes after too long a stay in the internal pipes, for instance after a long absence.

What can be done ?

•    Renew the water in the pipe before using it for human consumption. For this, let your faucets run for 1 to 2 minutes. If the problem persists, waist no time in contacting your local branch.
•    Renew the water in the hot water pipes of your home to prevent the growth of bacteria in warm stagnant water. Besides, it is not advisable to use hot water from the pipes to prepare hot drinks or food. It is better to use cold water that is then heated.

CDE suggests that its customers empty their water-heaters every quarter.

Any non-compliance should be interpreted as a signal that should lead to investigations and immediate corrective actions from the operator in order to return to a situation of compliance.

•    The taste of chlorine in water

Under the plan to strengthen disinfection in distribution systems, the dose of chlorine in the network was increased to 0.5 mg/litre. For comparison, the World Health Organization estimates that chlorine poses no health risk at less than 5 mg/L.

•    What role does chlorine play in drinking water ?

Chlorine is used as a disinfectant to treat drinking water. It is currently the most used product for this purpose and most effective for the elimination of pathogens and the safe transportation of water in pipes. It effectively prevents the multiplication of germs in water pipes, from the treatment plant to the consumer’s tap. The presence of chlorine in drinking water is therefore in response to a health requirement. It is guarantee for the health of consumers. However, tap water can sometimes have a slight taste of chlorine that some consumers cannot withstand. To eliminate this taste, put the water in a jug and let it be aerated for a few minutes before drinking. You can also put your jug of water in the refrigerator: the temperature will neutralize the chlorine taste.

•    Quality Degradation in private facilities:

These are private storage facilities for drinking water comprising of cisterns with a pumping system and storage tanks. Reservoirs are a place of choice for the deposition of sediments and, thereby, a risk zone for the degradation of water quality; they must be cleaned frequently. There should be draining and cleaning of these facilities at least once a year.

Standard procedure for cleaning and disinfection of a tank:

• Isolating the reservoir
• Draining the reservoir
• Maintaining and verifying faucets, stop-gates, valves, mixers, filters, protective devices
• Rinsing the walls and the floor with removal of settled matter
• Spraying the solution of bleach on the walls and floor
• Rinsing the tank
• Renewing the external seal to avoid any infiltration of water that can contaminate the water stored
• Limiting the infiltration of daylight
• Changing the ventilation system of the tank (removing aeration caps above the water level and establishing a ventilation system with horizontal wall-mouth, filters and air ducts).