Water Quality in Oman
Surface Water Quality
According to the Joint Monitoring Programme (JMP) report  entitled Progress on Drinking Water, Sanitation and Hygiene: 2017 Update and Sustainable Development Goal Baselines, released by the United Nations Children’s Fund and the World Health Organization, 97% of water in Oman is free from contamination and all residents have access to water. Moreover, 91% of residents have instant access to piped water, meaning only 9% have to wait for water to arrive in tankers. Water conservation and health experts  say that this is an excellent showing on the part of the government, and this number will improve further in the future. At the same time, the water in the Wadi Dayqah dam is of a high enough quality to satisfy irrigation requirements as well as domestic water supply after treatment.
The quality of well water differs from place to place. In places near the sea, the electric conductivity (EC) may reach 10 dS/m, owing to the pumping of groundwater at rates higher than the secured discharges, leading to saline seawater intrusion into agricultural lands. In most of the coastal area, salinity has increased gradually since 1988, when the expansion of agriculture reached its peak. The increasing salinity is probably the single most economically devastating water resource problem currently facing Oman.
The use of agrochemicals, both fertilizers and pesticides, is a widespread and potentially serious hazard to groundwater quality where, as is the case in most of the sultanate, groundwater is unconfined and most soils are sandy loam with low organic content (low water-holding capacity and high deep-percolation).
Sanitation and Wastewater Treatment Network
In 2010, it was reported that only 20% of Muscat’s residents were connected to the sewage network. The implementation of a sewage network project in late 2015 by Haya Water was expected to connect up to 86% of Muscat’s population to the sewer system. More than 402 sewage treatment plants (STPs) are recorded in the database of the Ministry of Environment and Climate Affairs (MECA), half of which are in Muscat, some belonging to the public sector and others to private owners such as hotels and industrial estates. STPs produced about 37,446 m3 of treated effluent (TE) in 2000, with individual plant capacity ranging from 8 m3/d to 15,000 m3/d. In 2010, that number had increased to about 97.8 MCM. Wastewater privatization projects (Haya Water in Muscat and Oman Wastewater Services Company in Salalah) now provide centralized sewer systems and treatment to all of the areas of the Muscat and Salalah governorates. The production capacity of the sewage treatment plant in Salalah was recorded at 27,000 m3/d in 2014.
Environmental and Health Risks
Small reverse osmosis (RO) plants have been built in rural areas (e.g. the Batinah region) where there is no other water supply option. An increasing number of Omani farmers are switching from a contaminated surface water source of irrigation water to an RO-desalinated brackish groundwater source. However, there is a major disadvantage to the RO process: the huge amount of brine produced. This brine is usually discharged not far from the farms using RO systems, contaminating groundwater sources and increasing salinity.
At a larger scale, the concerns mainly revolve around the concentrate and chemical discharges into the sea. Most desalination plants discharge their brine directly into the sea. In some cases, the brine is partially treated or mixed with seawater before disposal in order to meet local environmental regulations, mainly on salinity, temperature and chemicals. If evaporation ponds are constructed properly, these are a much more environmentally friendly option than dumping into the sea. Other important environmental factors are the emissions of greenhouse gases and air pollutants, as desalination is an energy-intensive process using fossil fuels. The desalination approach is in danger of shifting the problem from water scarcity to energy dependency, and from the stressed freshwater ecosystems to the marine environment. Therefore, the water-energy nexus approach should be considered. In order to safeguard the sustainable use of desalination technology, the potential environmental impacts of desalination projects need to be evaluated, adverse effects mitigated as far as possible, and the remaining concerns balanced against the impacts of alternative water supply and water management options. Environmental restrictions are expected to increase with time in order to mitigate the impact of desalination plants on the environment.
An additional and emerging threat to the desalination industry is from harmful algal blooms (HABs, commonly called red tides). High-biomass HABs can restrict flow in desalination plants by clogging filters, but other impacts include fouling of surfaces due to dissolved organic materials that can also compromise the integrity of RO membranes. Such HABs produce toxins that could be harmful for human health and fish. Many players in Oman are joining forces to come up with solutions to prevent and manage this risk, for example the Research Council of Oman, Middle East Desalination Research Center (MEDRC), Sultan Qaboos University and the Ministry of Agriculture and Fisheries. MEDRC has coordinated an international project to monitor such HABs.
 Joint Monitoring Programme (JMP) report, 2017, ‘Progress on Drinking Water, Sanitation and Hygiene: 2017 Update and Sustainable Development Goal Baselines’, United Nations Children’s Fund and the World Health Organization.
 Available at: http://www.timesofoman.com/article/120055 . Accessed on 11/4/2018.
 Zekri, S. et al., 2014. ‘Managed aquifer recharge using quaternary treated wastewater in Muscat: An economic perspective.’ International Journal of Water Resources Development, vol. 30, no. 2, pp. 246-261.
 al-Lawati, S. et al., 2017. ‘Wastewater and Sludge Management and Research in Oman: An Overview.’ Journal of the Air & Waste Management Association, vol. 67, no. 3, pp 267-278.