This short chapter on water management will give some important guidelines for proper water distribution in situations such as refugee camps, transit camps, resettlements and new settlements before a permanent water supply system is installed. It is focusing on a supply system, which distributes the water to the population through outlet distributors.
The amount and quality of water to be made available for each person will depend on the health status and living conditions of the people and the water situation in a given area.
Therefore, good water management means to make all potential sources for safe and good water accessible and to share them in a way that everybody will benefit, keeping in mind that the environment will not suffer and the water use will be kept at a sustainable level.
In most places, there is enough water, but it is unevenly distributed! These water shortages can result from "causes of war" in regions, quarrels in villages and stress in families.
The water demand of a population is very dependant on the cultural context, the established habits and their immediate living situation. However, organizations and governmental bodies including the UN have discussed some minimum standards of water supply as required by each person.
Sphere Standard: the chapter on minimum standard of water demand says that a person needs 15 litres of safe water per day.
This would include drinking water, water for personal hygiene and water for washing. This has to be seen as the minimum for a limited time period.
As soon as a family lives in a more permanent shelter or house, which in a rural context includes some kitchen use, gardening and some small animals, the water consumption will increase substantially.
However, in catastrophic situations and under very difficult circumstances, a realistic goal is to maintain safe water supply for a shorter period at not less than 4 litres per person per day.
Every effort should be made to increase this amount as soon as possible to reduce the risk of diseases and to improve living conditions.
A basic water management tool is always to have a current calculation of water demand and water supply to have a monitoring reference for the work.
Water Supply Potential
To manage your water supply system, the daily potential of water delivery has to be calculated (estimated) based on the technical details available. A water system consists of several elements:
All elements need a proper description, to make full use of the capacity available through alternative combinations of the elements. It is obvious that the element with lowest capacity will limit the potential water supply of the whole system.
The water source might be a river, a lake, a well or a water channel. Estimate the daily and/or continuous potential of water the source can deliver.
In many cases, the water from a given source has to be shared with other users. Proper demand and supply calculations, combined with proper negotiations from the beginning, reduce the risk of problems with other communities or authorities.
Most often, water has to be treated to provide proper quality drinking water. Our Emergency Water Purification Unit MEL 4.000 has been sized to produce 4.000 l/p/h equivalent to 60.000 l/p/day and it is equipped with a system completely protected into a steel container 6 x 2, 4 x 2, 4 meters. (Total weight of the unit (empty): 3.500 Kg).
To obtain proper quality drinking water, the system has been provided with:
·Active Carbon Filters
·Reverse Osmosis Membranes
Accessorized with :
·Power Diesel Generator
·Internal High Pressure Pump
·Drinkable Water Storage tank (10.000 litres capacity)
Drinkable Water Outlet Distributor
·Control Instruments for Pressure, Conductivity, Water Quality
·Circuit for Membranes Cleaning
·Outside suction pump and hoses
·Outside discharge pump and hoses
·Outside additional drinking water tanks
·Photovoltaic power production
For more details, consult our Technical Data Sheet rev. 1 dated 25.09.03 enclosed.
Water transport may involve both the transport of raw water to the Unit and the transport of treated water to the end points.
Drinkable water can be transported with trucks or can be piped to specified points of distribution. In pipes, water can flow by gravity or can be pushed with a booster pump. The transport capacity of a pipe is given by its diameter, length and pressure difference.
The pressure difference is due to the difference in altitude of entry and exit point (head difference), and pressure loss due to friction within the pipe (friction loss). To calculate the capacity of a pipe for a given situation, some fundamental engineering considerations have to be made (use specific tables and calculations for piping).
The transport of drinkable water to the distribution points is also depending on the same parameters as above when distributed through a pipe system. Transporting water via trucks to distribution points is often the only way to reach remote settlements. It gives flexibility in reaching people where they may be staying. However, transporting of water is an expensive operation requiring good management to be effective. For more permanent situations piped water to distribution points either by gravity or by pumping are preferred.
Furthermore, our Unit has been provided with an outlet distributor to be mounted outside of the container.
Water may have to be stored in different phases of a water supply system:
- Storage at the water source;
- Storage for distribution
The total storage capacity in a supply system should be in the range of one to two days' water consumption. The higher the storage capacity, the more safety for supply is built into the water supply system, making it more independent of technical problems and sudden supply shortages.
1) Storage at water source
If the water source originates from a river, a lake or a channel then raw water storage it is not required. If the water source only gives a small quantity of water per hour from a well, a storage system can collect water throughout day and night and bridge the gap between yield of the water source and the water needed during the day. This is often the solution for small springs or wells with limited yield.
2) Storage for distribution
For gravity fed distribution systems, water is pumped to a storage tank placed at a sufficiently high point in the terrain, from where a pipe system or flexible hoses feeds to different distribution points. Gravity fed distribution systems are easiest to handle for the party responsible for water supply.
Water is normally made available to families through water stations (tap stands) where people come and fill up their containers i.e. buckets or cans. The capacity of a distribution system is a direct function of the filling time for a given quantity of water. The filling time depends on the pressure in the pipe at the tap and the tap characteristics. In addition, when distribution capacity is critical, it is important that the line up of peoplefor water collection is well organized. Water distribution capacity thus contains both physical parameters and management factors.
It means that the population can be served their daily need of drinking water during about 14 hours with this distribution network. With approx. 14 hours of daylight this may be considered acceptable.
Drinking Water Supply
Most often only treated drinking water is distributed to the families. This is the case in all systems, where water is delivered through water stations where each household will come and get their daily water ration. This mean that all water served to the population is drinking water. However, in cases where treatment capacity is limited or purification highly expensive, drinking water can be provided separately from other water sources.
If water supply is split in drinking water and household water, the water management system needs to be carefully planned, proper training of the population is needed and the daily water operation needs proper supervision.
Drinking water is then distributed at specially designed taps and the people have to be very careful and follow the hygiene procedures as instructed and keep drinking water buckets/jerry cans identified and separate from other water buckets. The maintenance team has to maintain and monitor that people have a good understanding of the situation and act accordingly.
In any drinking water supply situation, the water distribution has to be supervised and clear instructions have to be given to the population. An important issue is the cleaning of the drinking water containers and how to keep the drinking water clean also in the household level. Sufficient containers have to be provided. The minimum daily requirement of drinking water is in the range of 3 to 5 litres per person.
For all water supply systems, situations arise when water becomes limited in quantity or water supply is basically non-existant. This might be due to technical failures of transport, piping, or treatment, or due to other reasons, like the water source running out of raw water.
In such situations, it is most important to act quickly when signs indicate the water shortage supply situation. Water shortages require immediate attention for careful water management.
Water for drinking will always have highest priority. In addition, it is important to distribute equally the remaining water to all persons in a community.
Water has to be conserved and used carefully because the duration of the water shortage usually is difficult to predict.
Actions to be taken immediately:
1)Inform community about water shortage;
2)Get current status on water available in storage tanks and drinking water demands;
3)Stop anyother water uses such as construction, washing, irrigation, etc.;
4)Make plan for fair water distribution and establish control to ensure that every family receives the same quantity of water;
5)All water in storage, also water in raw water tanks, settlement tanks, irrigation tanks can be treated for drinking water supply;
6)Treat available water, control consumption, distribute carefully and fairly;
7)Start looking for other water sources;
8)Consider taking water from other sources before all water in storage is used.
A tentative emergency plan of action on how to manage the water shortage should be developed as early as possible in any water supply scenario. No time should be lost in the early stage when signs of a possible water shortage are recognised. Having both the different scenarios and settings in mind, fig. 2 and 3, water purification solutions can be summarized under the following few key points:1. Water purification as production per day and persons served per day.
2. Water purification considering the trade off Quantity vs. Quality.
3. Type of water purification.
Fig. 1: Production of water per hours vs. daily production with different time periods ranging from to 20 hours.
Water purification units exist in the production range from 10 litres (0.01 m3/h) to 100.000 litres per hour (100 m3/h) or more. With different operating hours per day and different amount to be distributed to people, the number of persons served varies from a few persons per day to several 100.000 persons (orange lines on diagram).
Absolute need of water per person: In the guidelines for the UN and WHO, a minimum of 15 litres of water per person per day (15 l/per/day) is given as a standard. However, experience shows that in extreme situations over a shorter period of time, we have been satisfied to deliver as little as 4 litres per person per day. But, it has always to be very clear that such a situation is really an emergency and any measures have to be taken to increase the water distributed, because there is a close link between water quantity distributed and incidence of disease in the population.
Looking into the most common user groups in the situations which is the focus of this manual, the water demand of individuals in smaller cities is indicated on the same diagram (Fig. 2) also giving a range of m3/h production. From this diagram it can easily be seen for which sector water purification of specific capacity is needed. E.g. for a field hospital, safe water in the range of 1 to 10 m3/h is needed to serve the staff of some 50 to 100 patients.
Fig. 2: This diagram shows on the back-ground presented in fig. 1, the range of water consumption per day for typical situations relating to humanitarian aid work.