The Fourth Challenge to Safe Drinking Water: Sustainability and Climate Change

Why Does Water Environmental Quality Matter?

Protecting the water environment is essential to sustainable drinking water treatment because polluted source water can increase treatment requirements and place additional pressure on water-supply systems. For low- and middle-income countries, urban water environmental quality can be particularly difficult to manage as populations grow and wastewater volumes increase.

Where wastewater receives little or inadequate treatment, pollutants can enter rivers, lakes, reservoirs, and groundwater. These water bodies may also serve as sources of drinking water, creating a connection between wastewater management and drinking-water treatment. Some assessments have reported extremely low wastewater treatment coverage in parts of Latin America, including estimates of around 2% in some middle-income countries. The exact percentage varies by country, period, and definition of treatment, but the broader issue is clear: inadequate wastewater treatment can increase pollution pressure on freshwater resources.

Poor source-water quality can also increase the complexity of drinking water treatment. Higher levels of suspended solids, nutrients, organic matter, microorganisms, salinity, or other contaminants may require additional treatment processes or more intensive operation. Protecting water sources can therefore reduce pressure on downstream treatment systems.

How Is Climate Change Affecting Drinking Water Security?

Climate change can make drinking water supply less predictable by affecting rainfall, evaporation, drought frequency, flooding, freshwater availability, and source-water quality. Many developing countries are already vulnerable to seasonal rainfall variation and severe drought. Water resources can change significantly during different periods of the year, making reliable drinking-water supply more difficult.

Climate change can increase these pressures by altering the frequency and intensity of extreme weather events. Drought can reduce river flows, reservoir levels, and groundwater recharge. At the same time, heavy rainfall and flooding can introduce large quantities of sediment, nutrients, organic matter, and microorganisms into surface-water sources.

As a result, climate change can affect both sides of the drinking-water challenge: Water quantity can become less predictable, while water quality can become more difficult to manage.

How Can Flooding Change Source-Water Quality?

Flooding can increase turbidity, sediment, nutrients, organic matter, and microbial contamination in rivers, lakes, reservoirs, and other water sources, potentially increasing the treatment burden. Heavy rainfall can accelerate soil erosion and transport pollutants from agricultural land, urban areas, and other surfaces into water bodies.

Flood events can contribute to problems such as sediment accumulation, eutrophication, landslides, acidification, and salinity changes in vulnerable environments. These changes can affect the quality of water entering drinking-water treatment facilities. Reservoirs and lakes may also experience changes in temperature and thermal stratification. Changes in water circulation can influence where certain substances accumulate and may complicate water intake management.

SDIC and TCCA for Water Disinfection

SDIC, or sodium dichloroisocyanurate (NaDCC), can be used for appropriate drinking water disinfection, household water treatment, and point-of-use water disinfection applications. Unlike large centralized treatment systems, household and small-scale water treatment may need to operate with limited equipment, storage capacity, and technical resources. This is particularly relevant to rural communities, remote locations, emergency situations, and households that rely on local water sources.

Sodium dichloroisocyanurate for water treatment provides a solid chlorine-based option that can be relatively convenient to transport, store, portion, and use when applied correctly. For household drinking water disinfection, the ability to store a solid product without transporting large volumes of liquid disinfectant can be useful where supply logistics are limited.

TCCA, or trichloroisocyanuric acid, is another solid chlorine-based disinfectant that can be considered for certain small-scale water treatment and disinfection applications. Its high available chlorine content means that relatively small quantities can introduce chlorine into water, while its solid form can simplify storage and transportation compared with handling large quantities of liquid disinfectant.

Can Household Water Disinfection Improve Water-System Resilience?

Household and point-of-use water disinfection can provide an additional layer of resilience when centralized drinking-water services are disrupted or unavailable. Extreme weather can damage pipelines, interrupt electricity supplies, affect pumping stations, or temporarily reduce the reliability of centralized water distribution. In such situations, households and small communities may need alternative ways to treat locally available water.

Appropriate household water treatment can help bridge part of this gap. For microbial contamination, chlorine-based disinfectants such as SDIC/NaDCC can provide a relatively simple and practical option for suitable point-of-use applications, particularly in areas without reliable piped water supplies. SDIC/NaDCC is available as a stable solid disinfectant with a relatively long storage life, slow loss of available chlorine under proper storage conditions, and no insoluble residue after dissolution. These characteristics can make it easier to store, transport, and prepare for use while helping maintain reliable disinfection performance where access to centralized water services is limited or inconsistent.

This does not mean household treatment should replace investment in centralized water infrastructure. Instead, decentralized and household treatment can complement larger systems and provide additional flexibility where centralized services are limited or temporarily disrupted.

Why Should Water Systems Move From Recovery to Adaptation?

Long-term water resilience depends on preparing for future risks rather than relying primarily on repairing systems after extreme events have already caused damage.

When financial resources are limited, disaster recovery often receives immediate attention. Infrastructure damaged by floods, droughts, storms, or other events must be repaired quickly to restore services. However, repeated recovery without sufficient investment in prevention can create a cycle of damage and reconstruction. A more sustainable approach places greater emphasis on adaptation and preparedness.

Water authorities and communities can strengthen resilience by:

These measures can help reduce economic and social losses while improving the ability of water systems to continue operating during periods of environmental stress.

Conclusion