Water storage
Water storage is a broad term referring to storage of both
Types
Groundwater
Aquifers receive water through two ways, one from precipitation that flows through the unsaturated zone of the soil profile, and two from lakes and rivers.[2] When a water table reaches capacity, or all soil is completely saturated, the water table meets the surface of the ground where water discharge in the forms of springs or seeps.[2]
It is also possible to artificially recharge aquifers (using wells), for example through the use of Aquifer storage and recovery (ASR).
Soil moisture
Groundwater is stored in two zones, one being the saturated zone, or Aquifer, the other is the pore space of unsaturated soil immediately below the ground surface. Soil moisture is the water held between soil particles in the root zone (rhizosphere) of plants, generally in the top 200 cm of soil. Water storage in the soil profile is extremely important for agriculture, especially in locations that rely on rainfall for cultivating plants. For example, in Africa rain-fed agriculture accounts for 95% of farmed land.[3]
Wetlands
Wetlands are basically sponges that capture and slowly release large amounts of rain, snowmelt, groundwater and floodwater. Trees and other wetlands vegetation slow the speed of flood water and more evenly distribute it across the wetland. The combination of increased water storage and flood water hindrances lower flood heights and reduce erosion.[5]
Ponds and tanks
Detention basins and water tanks can be defined as community-built and household water stores, filled by rainwater, groundwater infiltration or surface runoff. They are usually open, and therefore exposed to high levels of evaporation. They can be a great help to farmers in helping them overcome dry spells. However, they can promote vector-borne diseases such as malaria or schistosomiasis.[6]
Detention basins are designed for temporary capture of flood waters and do not allow for permanent pooling of water and therefore do not make viable or reliable sources of water storage.[7] Retention basins are similar to detention basins for flood control management, but are built for permanent pooling to control sediment and pollutants in the flood water.[8]
Dams and reservoirs
In the past, large
Planting basins
Contamination
As of 2010, it was reported that nearly half of the global population depends on in-home water storage due to a lack of adequate water supply networks.[12] Many of the in-home solutions have improvised from available materials. It has been suggested that the lack of proper tools and equipment for construction, leads to a system more likely to contain breaches, making them more susceptible to contamination from the environment and users.[12]
Common factors
- Roofing Materials:[13] In certain parts of the world uncoated lead flashing is used as a roofing material. Researchers found on-site water storage of rainwater was more acidic, and contained elevated levels of heavy metals in a study conducted in Australia from 2005–2006.[13]
- Hand-washing: When water is stored in tanks for consumption hand-washing can become a factor if the tank lacks a proper faucet system, or if there is a lack of education on the risks posed by using hands for water consumption. It was found in a 2009 study that water tanks in Tanzania contained 140-180% more fecal indicator bacteria than the water they were supplied with.[12]
- Fertilizer Runoff [14]
Common risks
Decontamination
In the event that a water tank or tanker is contaminated, the following steps should be taken to reclaim the tank or tanker, if it is structurally intact. Additionally, it is recommended that tanks in continuous use are cleaned every five years, and for seasonal use, annually.[15]
- Clean: Drain the tank(er) of any remaining fluid, making sure to capture any hazardous fluid to be properly disposed of. Then scrub the inside of the tank with a detergent, and hot water mixture.[16]
- Disinfect: Fill the tank a quarter full with clean water. Sprinkle 80 grams of granular high-strength calcium hypochlorite (HSCH) into the tank for every 1000 litres total capacity of the tank. Fill the tank completely with clean water, close the lid and leave to stand for 24 hours.[16]
- Flush: After the chlorine solution has sat in the tank for 24 hours, flush out/empty the storage tank. Do not drain the tank into a septic system or adjacent surface water body. Continue flushing until the waste water is clear and no chlorine odor is detected.[15]
- Test: Once the storage tank has been thoroughly flushed, test for free chlorine residual to ensure it is non-detectable. Once a non-detectable chlorine residual has been obtained, collect operational & maintenance (O&M) total coliform bacteria water samples.[15]
If the test results are negative for bacteria, the drinking water is considered safe to use and drink.
See also
References
- PMID 20979609.
- ^ a b c "Groundwater" (PDF). EPA.gov.
- IWMI.
- ^ The Wetlands and Poverty Reduction Project, Wetlands International, 12-2005
- ^ "Why are wetlands so important?". EPA.gov.
- PMID 10376281.
- ^ "Detention Pond Management Practices Fact Sheet" (PDF). Dauphin County Conservation District.
- ^ "Best Management Practices for Stormwater Runoff" (PDF). Laramie County Conservation District. Archived from the original (PDF) on 2018-10-24. Retrieved 2018-04-25.
- IWMI
- ^ a b "Dams and Reservoirs". MIT Water for All.
- ^ Diverse water sources key to food security: report, Reuters, September 5, 2010
- ^ PMID 20222746.
- ^ PMID 1324.
- ISSN 0036-8075.
- ^ a b c Maine CDC Drinking Water Program (October 2017). Cleaning, Disinfecting, and Flushing Drinking Water Storage Tanks at Small Public Water Systems (PDF) (Report). Augusta, ME, US: Maine Center for Disease Control and Prevention.
- ^ a b "Cleaning and disinfecting water storage tanks and tankers" (PDF). World Health Organization.