Additionally, there are problems with water quality in Sanaa due to wastewater getting into water pipes and also leaching down into the aquifer. A 2018 study found the water exceeded the limits for dissolved solids and coliform bacteria, including ''E. coli''. Sana'nis tend to view the city's tap water as contaminated, choosing instead to buy filtered water in containers for drinking and cooking, which costs significantly more. Private kiosks using reverse osmosis to filter poor-quality groundwater are also popular.