Is Your Infrastructure Ready? 2026 Pillars for Water Supply

Stay ahead of 2026 water supply trends. Learn the pillars for modernising ageing infrastructure, ensuring water security, and meeting new efficiency mandates.

By 2026, the definition of ‘reliable’ water infrastructure has shifted from simple hydraulic capacity to complex, data-driven resilience.

As global water stress hits new peaks, the traditional ‘pump and pipe’ model is being replaced by critical pillars that integrate digital twins with biological filtration.

If your current master plan hasn’t accounted for these 2026 standards, you’re designing for a world that no longer exists.”

Water supply involves providing convenient and sufficient access to safe, potable/palatable water within a given design area and design period.

Also, water supply schemes have to fulfil these requirements at the minimum cost of construction, operation and maintenance of the project.

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Water supply design includes

Water supply design includes the following:

• Determination of water demand
• Identifying the water source and its capacity
• Designing of the gravity main where the diameter, velocity and material of the pipe will be determined
• Determination of water storage tank capacity
• Designing a distribution network where the diameter, material type, discharge and its velocity will be determined

Water sources

After estimating water requirements for the water supply scheme, the second step is to search for nearby water sources that may be able to supply the required amounts of water.

The following are the sources of water on the Earth:

Surface sources

Surface sources include:

• Ponds, lakes, streams and rivers
• Storage reservoirs

Underground sources include:

• Springs
• Boreholes

Water source selection

The process of choosing the water source of water supply scheme depends on

• Source availability
• Water quality
• Economic feasibility

Surface Water Intakes

Surface water intake is the first point where the water is taken from the source. The source can be a pond, lake, river, stream or canal.

The basic function of the intake structure is to facilitate the safe withdrawal of water from the source, then to discharge it into the withdrawal conduit, which carries it up to the water treatment plant.

River/ stream intakes

In Water Supply, Water from the river is always drawn from the upstream side because it is free from contamination caused by sewage disposal.

Also located at a place which will not erode easily. The intake should be deep enough to avoid being above the minimum recorded river level, yet not so deep as to capture bottom sediments.

Special intakes

There are two types of special intakes:

1. Simple strainer and tripod intake- This type of intake is installed in a small stream where the discharge is nearly constant.
2. Weir intake- This type is used when the stream water level is low and must be raised to form an intake. Then, a weir would be ideal.

Location of intake site

Points to consider:

• The intake should be located at a point where the highest-quality water will be withdrawn from the source.
• The selected site permits greater water withdrawal even during the driest period of the year.
• The site remains easily accessible during floods and should not get polluted.
• Never located at the downstream or in the vicinity of the point of disposal of wastewater.
• Sediment transport, erosion of the river banks and silt concerns.

Gravity Main

In Water Supply, the pipelines are laid or installed to convey water from a high-level source to the treatment plant or storage tank at lower levels by the mere action of gravity, without any pumping.

For proper functioning of the system, the difference in head available between the source and other localities must be sufficient to maintain adequate pressure at the consumer’s doorsteps, after allowing for the frictional and other losses in the pipes.

This method is the most economical and reliable since no pumping is involved at any stage.

The system is designed to leave only the minimum permitted available head to the consumer, and the rest is consumed by frictional and other losses.

This will keep leakage and waste to a minimum and reduce the required pipe sizes. Gravity main is, of course, the most preferable in respect of economy in construction, operation and maintenance.

In Water Supply, the main shall always be of sufficient size that the total quantity required for the projected peak-day demand can flow through the pipe for 24 hours.

The main should be as far as possible on a constant falling gradient, avoiding high points and low valleys.

When static pressure exceeds the allowable pipe pressure, a break-pressure tank with a ball valve should be installed.

Rock outcrop should be avoided, as drilling and blasting a trench in a rock is highly expensive.

The pipeline should be aligned around the rocky areas by using large-radius bends, or, better still, by using the slight deviation angle at each pipe joint, staying within the limits of 50 for small-diameter pipes, reducing to 30 for the largest-diameter pipes, as prescribed by the manufacturers.

Concrete anchors should be constructed at every 200 meters on all gradients and at much lesser distances in steep gradients, also at all horizontal and vertical changes of direction and at all equal tees and valves.

A non-return or reflux valve can be located up to 3 to 5 km away to facilitate maintenance and repair, and to reduce water hammer.

Union of flanged joints should be provided every 350m to 500m in all pipelines for inspection, maintenance, and replacement.

The gravity mains are so designed that the available pressure head is lost entirely to overcoming the frictional resistance to water flow.

The velocities to be generated are therefore maintained so that they are:

• Neither too small to require a large diameter pipe.
• Nor too high to cause excessive loss of pressure head.

Storage Tank

The aim of the water storage tank in the distribution system is:

• To balance the demands of the user and the availability of water.
• To balance the uneven demands made by the users throughout the day.
• To furnish water for such emergencies as firefighting or accidental breakdown.
• To provide possibilities of repairing in case of breakdown of the transportation system or unexpected storage in the supply of water.

Distribution Systems

The last stage in the water supply scheme is the distribution of water to consumers. The system consists of large-diameter mains, submains of intermediate pipes, minor distributors of small-sized pipes, hydrants, valves, and meters.

The distribution systems are classified as follows:

• Gravity system.
• Pumping system
• Dual system or combined gravity and pumping.

Gravity system

In this system, water is distributed by gravity. Water should have sufficient supply pressure at all points in the system.

In the Water Supply Scheme, this system is adopted when the source of supply is available at a sufficiently higher level than the place of distribution.

Pumping system

The system where water is conveyed from the source to consumers using a pump.

Dual system

Water is conveyed from the source to consumers by using both pump and gravitational forces.

Layout of the distribution system

The following patterns are commonly used for pipeline layouts that distribute water to consumers.:

• Grid system
• Dead-end system/Branched system

Grid system

In this system, water mains and branches are laid in rectangles. Water mains, sub mains and branches are all interconnected.

This is the most widely used system, especially in town areas and well-planned areas. In a gridiron system, water flows to different points via more than one route; hence, first of all, the quantities of flow going via each route must be determined.

In a water supply scheme, the flow through different routes depends on the sizes of the pipes, and hence they must first be assumed to be routed through different routes.

The loss of head taking towards a point at the other end of the circuit is then estimated via each route. If the assumed pipe sizes and flow distribution are correct, these head losses will be equal.

Advantages of the grid system

• During breakdown or repairs, water can be supplied from other pipelines.
• In case of fire, water is available from all directions.
• Water circulates freely, as there are no zones of stagnant water, which can support pathogens
• Loss of head is minimal throughout the system.
• Relatively safe against bursts

Disadvantages of the grid system

• Exact calculations of pressure and the pipe diameter are difficult.
• Longer pipes are required, hence costly.
• More valves are required for operation.

Dead-end system

In this system, one main supply pipe is provided, from which some submain pipes originate. Each sub main then divides into several branch pipes called laterals.

Service connections are given to the consumers. This system is adopted for towns which have developed randomly. The calculation is done for each line; i.e., we should treat each line independently.

Advantages of the system

• The discharge and pressure at any point can be easily calculated
• The diameter of the pipes is smaller as they serve only a limited population
• Fewer valves are required for operating the system.
• Is cost effective because it uses small quantities of pipes

Disadvantages of the Dead-End System

• During pipeline breakdowns or repairs, the downstream population may not receive water.
• Adequate water for firefighting may not be available
• Due to Dead ends, contamination of water may occur
• Loss of head is relatively high

Water Demand and Water Production

In a water supply scheme, total water demand is calculated based on the number of people served, including the percentage loss due to leakages, while water production is the amount of water available from sources, e.g., dams, rivers, springs, boreholes, etc.

These are initial data for a water project design. Water quantity is the primary criterion for designing a water project, enabling the determination of the sizes of all components.

Categories of water demand

The various categories of water demands are classified into the following:

• Domestic water demand
• Industrial, commercial and institutional water demand
• Water required compensating losses, thefts and wastes
• Water demand projections
• Variation in Water Consumption

Selection of Water Demand

The selection of water demand in the design area includes:

1. Estimation of actual water requirements at present.
2. Addition of water demand in future based on assumptions on developments.

Thus, the design demand of water supply will be (1 + 2 above).

Water Pressure

To avoid bursts and leakages in the water supply system as well as undersigned noises and pressure shocks, the pressure in the main pipe should be restricted to not more than 60m pressure head for a gravity main and about 105m pressure head for a rising main, and the static pressure at the domestic point should be not less than 5m head.

Water Quality

In the Water Supply Scheme, Water quality should meet international standards or WHO criteria. For rural water supplies, the revised Tanzania temporary standards can be used.

An appropriate treatment plant should be designed for all surface water sources.

Design Period

In the Water Supply Scheme, the design period is the period for which the project’s long-term projected demands are estimated for a least-cost project.

The project’s design period is categorised as short-term (5 years), future (10 years), and ultimate (20 years).

In the demand forecast, precautions should be taken to avoid overestimating or underestimating the water demand.

Overestimating demand may lead to unnecessary costs. On the other hand, for underestimation, more time should be spent on the demand analysis and projections.

Average daily demand is the result of adding together domestic, agriculture, livestock, public institution, industries, commercial, fire demand and losses.

Air Valves and Washouts

In the Water Supply Scheme, an air valve can be placed in the main lines at higher points in the pipeline to release accumulated air during operation (Air lock).

However, in flat areas it is preferable to provide an air valve at every 1000metres interval. While washout should be at all low points of the pipeline.

Pipe Laying Across the River/ Stream

In a water supply scheme, pipes should be laid in well-prepared trenches, 0.6m wide and 0.75m deep, for pipes up to 100mm in diameter. For larger diameters, trenches 0.8m wide by 1.0m deep are required.

The pipe should be laid on a prepared, level bed cushion of sand or soil free of stones under the pipe, and the backfill material should be free of stones.

In case of road crossing or river a special care should be taken. A minimum of 1.0m cover should be provided at road crossings, but it is more advantageous to use sleeves of DI, CI, or MS pipes.

In a water supply scheme, the cover and its protection should extend up to 3m beyond the road width on both sides. For river crossing, the main pipe should be laid 1.0m below the river bed covered by a concrete cover.

Where it is not possible to lay the pipe below the river bed, the pipe can be laid over the river by constructing the supporting pillars (anchor blocks) at the river bank, where the flood level will not reach the pipe level.

Choice of Pipe Materials

The choice of pipe material should be made based on quality, durability, strength, and price point from an economic perspective, because plastic pipes are preferred over galvanised steel pipes because they are cheaper.

Where the soil condition does not allow, e.g. pressure requirements are of high-class pressure pipes, such as GS, are used for large and small sizes respectively.

In the Water Supply Scheme, GS pipe must be used in intakes, tanks and break pressure tanks; nevertheless, GS pipes are used in road crossings, river crossing and places where, by any means, the pipes are to be exposed over the ground.

Pipes are available in various materials, sizes and pressure classes. The common pipe materials are: –

• Polyvinyl chloride (PVC)
• Polythene (PE)
• Galvanised steel pipe (GS)
• Ductile iron (DI)
• Cast iron (CI), etc

Selection of pipe materials should be based on economic considerations, i.e., quality, cost, durability, and strength.

For instance, it is economical to select plastic pipes rather than galvanised steel pipes, which are expensive except where pressure is extremely high.

Also, in the Water Supply Scheme, GS pipes are normally used where pipes are exposed over the ground, in rocky areas, or at road crossings, river crossings, intakes, storage tanks, etc.

Pipe classes and ranges in Pressure

In a water supply scheme, Pipes are classified according to their pressure rating, with plastic pipes (PVC, polythene) classified as class A, B, C, etc. Class A has the lowest capacity, and steel pipes are classified into medium and heavy-duty.

In a water supply scheme, Heavy-duty classes have a high capacity to withstand pressure. The following table shows the normal working pressure of different pipe classes.

Flows in Pipes

The empirical Hazen-William formula is simple for determining the flow of raw or portable water at normal temperature; it can be relied upon to give results of sufficient accuracy for all practical purposes.

The formula can be expressed as follows:

Where:

• Q = Quantity l/ sec
• D =Diameter of pipe in (mm)
• I =Hydraulic gradient (dimensionless)
• C =Friction coefficient (dimensionless)

Recommended – value of C: Steel pipes -100 and Plastic pipes-140. (Ministry of Water and Irrigation Design Manual – 1977)

The Pipe sizes and recommended velocity are tabulated here:

Summary of the Pillars for Water Supply

To ensure a resilient water system, we must balance four critical areas:

• Technical Soundness: The engineering must be robust, from extraction through the final faucet. This includes maintaining pressure, ensuring water quality, and minimising “Non-Revenue Water” (leaks).
• Financial Sustainability: A system that cannot pay for its own electricity or repairs will eventually fail. This involves fair tariff structures and efficient billing.
• Institutional Governance: Clear laws, transparent management, and a skilled workforce are the “brain” of the operation.
• Environmental Stewardship: Protecting the source (aquifers and watersheds) ensures that we aren’t drawing from a bank account that never gets a deposit.

The Path Forward Water Supply Scheme

Achieving a sustainable water supply is an ongoing process rather than a final destination. As urban populations grow and climate patterns shift, these pillars must be adaptive.

Success in Water Supply is measured not just by the presence of infrastructure, but by its reliability.

A buried pipe is a liability if it’s empty; it’s a service only when it consistently delivers safe water to the community.

Therefore, by strengthening these pillars, we move away from “crisis management”—patching leaks and hauling trucks—toward resilient utility management.

This foundation is what allows communities to thrive, businesses to operate, and public health to be guaranteed.

That’s All.