Most industrialized countries use a centralized water supply approach to control, treat and distribute water among their populations. This has proved an effective way of reaching the various regions in nations where a developed infrastructure is in place. However, there are problems with centralized supplies including leakages (which amount to 45 million cubic metres a day), bacteria that can develop when water stagnates, and uneven water quality across different areas.
Another approach is to use a decentralized system. This is common in developing parts of the world without the infrastructure for centralized supplies, but can also be used in economically advanced countries to provide supplementary low-cost, efficient and good quality drinking water at the local level.
Decentralized water systems use smaller-scale purification methods to turn local water supplies into drinking water. The water generally comes from three sources:
• Waterways such as local lakes and rivers, where water can be collected and purified locally. This is most frequently done when water is distributed at a communal level;
• Groundwater sources such as dug or drilled wells;
• Recycled water supplies such as rainwater or wastewater, which is collected through a recycling system. This is suitable for domestic supplies operated at individual household level.
Decentralized supply systems can be loosely categorised into two types. These are:
• Household water treatment systems (HWTS) which supply water to individual households, filtrating the water either at point of use (via a small unit close to taps) or point of entry (via a larger storage tank which then supplies the water to the whole building). These are ideal for sustainable use of recycled rainwater and wastewater.
• Small-scale systems (SSS) which collect, treat and distribute water locally. This can be done at community, neighbourhood or commercial organizational level, turning saltwater, rainwater or wastewater into premium drinking water.
Communities in several developing countries have made successful use of decentralized drinking water systems, such as in Mali and Bolivia. But the decentralized approach is something that offers benefits even to places with a working central water supply by providing a sustainable alternative.
Areas with a centralized water supply can benefit from combining both centralized and decentralized systems, using the decentralized approach to create a drinking water supply and thereby reducing the pressure on the main water network. Advantages include:
Decentralized water supplies can improve microbial water quality and reduce contamination between treatment and use because filtration is done much closer to the point of access. Although most countries in Europe, as well as places such as the US, generally have good quality drinking water, levels of chemical pollutants and microplastics – although not dangerous – can still be found in centralized supplies.
Added to this is the issue of variation of water quality across different regions, with some areas placed much further away from the water source than others. Water has to travel long distances after the point of filtration, meaning that it is less “pure”. Decentralized filtration systems greatly reduce the distance that treated water has to travel, resulting in a better and safer product.
Although decentralized water systems involve costs to install, they save money in two ways. Firstly, systems are cheaper to maintain and less is lost through leakage waste. According to the World Bank, leaks in centralized water systems across the globe cost around $14 billion annually and infrastructure spending to upgrade piping networks is expected to cost $41 trillion between 2005-2030.
Secondly, water sourcing is generally cheaper as there is less reliance on fresh groundwater sourcing and more emphasis on utilizing recycled water. This means a vast reduction of expensive groundwater pumping procedures.
Finally, there is the environmental benefit of sourcing water locally and through sustainable methods. We are on the verge of a global water crisis, with demand predicted to outstrip supply by 2040, meaning that we need to review the way we distribute and supply water. Decentralized systems not only help preserve water by reducing leakage waste, the systems are also less energy-intensive so save on gas and electricity too.
With advances in technology, hi-tech systems such as the Q-Drop can operate powered solely by renewable energy. Such systems enable households, businesses, and communities to access high quality and cheaper drinking water while helping to preserve the environment at the same time.