The most common way to purify water in an overhead tank, specifically concerning disinfection, is through chlorination.
Disinfecting Your Water Tank
Ensuring the water in your overhead tank is safe for use often involves a process of purification, primarily focused on disinfection to kill harmful bacteria and microorganisms. While purification can encompass filtering out sediment and other particles, a critical step for health safety in a stored water supply like an overhead tank is chemical disinfection.
Chlorination: The Standard Method
According to common practices, the most frequent and effective method for disinfecting a water tank is chlorination. This involves adding a chlorine-releasing agent to the water to sanitize it.
One common way chlorine is introduced is by using high-strength calcium hypochlorite (HSCH). This compound, when mixed with water, releases a significant volume of chlorine, typically between 60% and 80% of its volume, which then acts as a disinfectant.
How Chlorination Works
Chlorine works by oxidizing cellular components of microorganisms, effectively neutralizing or killing them. This process helps prevent the growth of bacteria, viruses, and other pathogens within the stored water supply.
The process generally involves:
- Emptying and Cleaning: The tank should ideally be drained and physically cleaned to remove sediment, sludge, and biofilm before disinfection.
- Introducing Chlorine: A calculated amount of chlorine solution (often prepared from HSCH powder or tablets) is added to the tank. The amount needed depends on the tank size and the desired chlorine concentration for disinfection.
- Contact Time: The chlorine solution is left in the tank for a specific period (contact time) to allow it to effectively disinfect the water and tank surfaces.
- Flushing: After the contact time, the chlorinated water is usually drained and flushed out of the tank and associated pipework until the chlorine smell is minimal.
- Refilling: The tank is then refilled with fresh water.
While the reference specifically highlights chlorination using HSCH as the primary method for disinfecting the tank, it's an essential step towards ensuring purified (safe) water is stored. Other purification steps, like pre-filtering incoming water, can also contribute to overall water quality in the tank.
It is important to follow recommended guidelines and dosages when using chemicals like calcium hypochlorite to ensure effective disinfection without creating harmful levels of chlorine in the water supply. Consulting local water quality standards or a professional is advisable.
