Improved access to drinking-water
Characteristics to quantify the state of drinking water supply:
Water should be
- physically accessible
- 50 to 100 liters per person per day
- from a source less than 1 kilometre from their home
- collection time should not exceed 30 minutes
Safe drinking water
Aspects for judging the quality of water
- bacteria, viruses, protozoa, worms
- indicator organism for faecal contamination: Escherichia Coli (E.coli)
- total dissolved solids
- taste and smell
Drinking Water Sources
- Surface Water
- Salt Water
- Others (e.g. treated wastewater)
- Centralized water treatment - Water delivery through net
- Community scale water treatment
- Treatment at household level
- Safe water storage necessary
Drinking Water Treatment e.g.
- Filtration (Sand, Membrane)
- Adsorption (charcoal, activated carbon)
- Disinfection (Chlorine, Ozone, UV Radiation)
- SODIS: a simple water treatment method using solar radiation
(UV-A light and temperature) to destroy pathogenic bacteria and viruses Microbiologically contaminated water is filled into transparent containers (PET-bottles) and exposed to full sunlight during 6 hours.
- solar disinfection only kills germs
- chemical composition of the water remains unchanged
- relatively clear water
- no matter what kind of water source
- efficiency depends on exposition time
- sunlight produces highly reactive forms of oxygen (radicals) in the water. These reactive molecules react with cell structures and kill the pathogens
- aeration of the water can be achieved by shaking the ¾ filled bottle for about 20 seconds before the bottle is filled completely and exposed to the sun.
- various types of transparent plastic materials are good transmitters of light in the UV-A range
- the use of bottles made from PET instead of PVC is recommended as PET contains much less additives
For more information see: http://www.sodis.ch/methode/anwendung/ausbildungsmaterial/dokumente_material/manual_e.pdf
Geogenic load –arsenic
- high arsenic levels can cause cancer of the skin, liver, lungs, bladder, kidney
- high arsenic concentrations e.g. in parts of India, Bangladesh, China, Thailand
Source: British Geological Survey http://www.bgs.ac.uk/arsenic/
Arsenic mitigation options:
Arsenic-Free Alternate Water Supply Technologies
- Safe Tube Wells
- Improved Dug Wells
- Rainwater Harvesting
- Deep Wells
Treatment of Surface Water
- Community-Scale Water Treatment
- Household-Scale Water Treatment and Safe Storage
Arsenic Removal Technologies
Source: Susan Murcott: Arsenic contamination: a worldwide call to action, water 21, April 2013 (https://issuu.com/christinadianparmionova/docs/arsenic_contamination_of_groundwater_sources)
Geogenic load – fluoride
overexposure to fluoride during childhood can lead to dental fluorosis:
– discoloured, blackened, mottled or chalky-white teeth
Chronic intake of excessive fluoride can lead to the severe and permanent bone and joint deformations of skeletal fluorosis.
Methods for removal of fluoride:
– Precipitation and coagulation
– adsorption (filter materials)
– membrane filtration processes
Source: http://www.nofluoride.com/Unicef_fluor.cfm ;IGRAC (2007): Fluoride in groundwater: Overview and evaluation of removal methods
Drinking water treatment - households –
- Takes advantage of existing water supply infrastructure (e.g. boreholes).
- Allows targeting of people most at need.
- Relatively easy and inexpensive to implement.
- Systems may not be operated correctly.
- Lifetime of chemical removal filters is difficult to predict, so it is hard to know when replacement is needed.
- Effective replacement requires supply chain and motivation.
- Routine monitoring is a challenge.
- Some populations can easily be excluded due to lack of information or financial resources.
Source: Eawag (Januar, 2015): Geogenic Contamination Handbook, Chapter 7
Simple Drinking Water Treatment
Multi Barrier Approach to Safe Water
- Source Protection
- safe storage
Water storage at household level
A safe water storage container should:
- Have a strong and tightly sealing lid or cover
- Have a tap or narrow opening at the outlet for access
- Have a stable base so it does not tip over
- Be durable and strong
- Be easy to clean
- A good storage container should also have instructions on how to properly use and maintain it.
Water storage – water distribution – water loss reduction
Recontamination in the delivery system must be prevented.
Water treatment at household level reduces the risk of pathogen transmission through drinking water. Safe storage of the treated water must be ensured.
In developing countries a big proportion of centralised treated water is lost on the way to the consumer.
Methods for real water loss reduction in distribution networks are
- infrastructure management,
- active leakage control,
- near-time repairs,
- pressure management.
Source: Dr. Haußmann, ISA Aachen, 2019
Analysis of Drinking Water:
- health protection
- guarantee of quality
Analysis of e.g. bacteria, viruses, microbes, taste, color, pH, turbidity, metals, salts
- effective confirmation of fecal contamination
- most E.coli are harmless
- some cause illness in humans like
- stomach cramps
- bloody diarrhea
- urinary tract infection
- can be distinguished from most other coliforms
- fecal coliform test
Nitrogen in water
Nitrogen components have a variety of effects on surface waters:
Norg -> strongly oxygen depleting
NH4-N -> oxygen depleting | pH > 8 toxic to fish, eutrophying
NO2-N -> eutrophying
NO3-N -> highly toxic to fish, eutrophying
Total Ammonia consists of both
- nontoxic NH4+ (ionized)
- toxic NH3 (un-ionized) forms
toxic form increases in proportion as
- pH and/or
- temperature increases.
Ammonia builds up in the water primarily by the metabolism of protein (nitrogen).
Ammonium ions can be nitrified and converted by microorganisms into nitrate (nitrification).
Health Risks Of Consuming Ammonia:
- Long-term exposure of even a small bit of ammonia can cause damage to the human body.
- Long-term ingestion of water with as little as 1ppm causes
- damage to internal organs
- issues in the lungs
- nervous system
- irritation in ears, nose, throat
- Water with more than 100ppm of ammonia can cause severe burning and scarring on skin and mucus membranes.
Source: Oregan Department of Human Services, Environmental Toxicology Section, 2000
Concentration in surface water
-> normally low (0–18 mg/l)
-> concentrations can reach high levels
----> refuse dump runoff or contamination with human or animal wastes
->fluctuates with the season
->may increase when the river is fed by nitrate-rich aquifers
Health Risks of Consuming Nitrate in drinking water:
- Causes severe detrimental health issues, yet most people consume it daily
- Nitrate should not surpass 10 parts per million (ppm)
- fight against blue baby syndrome = an infant becomes deprived of oxygen
- Increases the risk of several different cancers
- causes defects in babies if their mother consumes it while pregnant.
Source: WHO, 2016: Nitrate and Nitrite in Drinking-water
- in unpolluted waters nitrite levels are generally low <0.1 mg/l N, e.g. drinking water
- nitrites come from fertilizers through run-off water, sewage and mineral deposits
Health Risks of Consuming Nitrite
-> level goal for nitrites (MCL) -> 1 ppm
-> Nitrites have the potential to cause (lifetime exposure) e.g.
- starchy deposits
- hemorrhaging (bleeding) of the spleen
Source: WHO, 2016: Nitrate and Nitrite in Drinking-water
The United Nations World Water Development Report 2015: Water for a Sustainable World
UNICEF/WHO (2017): Safely managed drinking water
WHO (2017): Progress on Drinking Water, Sanitation and Hygiene - 2017; Update and SDG Baselines