Water Supply

Provide water

• 1. in impeccable water quality

• 2. in sufficient quantity

• 3. with sufficient pressure

Every time and at any point in the supply area

Water is analyzed by testing its physical, chemical and microbial characteristics

The EU Standards:

• The mcirobiological parameters, E. coli and Enterococci must be absent from samples

• 26 chemical parameters (e.g. arsenic, nickel, lead and presticides), are set because of their impact on human health

• 20 indicator parameters (e.g. chloride, sodium, taste, odor, turbidity) do not pose a direct threat to human health; nontheless, they have indirect relevance for water quality

• further Developments

  • Updated list of standards includes 18 new or revised parameters: naturally occurring harmful substances such as uranium; emerging contaminants such as per-fluorinated compounds

  • Three disinfection bioproducts or distribution impurities such as chlorate and endocrine disrupting ompounds such as bisphenol A

  • Microplastics are addressed in the proposal as an issue of emerging concern

Drinking Water Quality Standards

Surface water resources

• Pounds and lakes

• Streams and rivers/ bank filtration

• Reservoirs/ Dams

• Oceans

Sub-surface sources/ Groundwater sources

• Springs

• Infiltration wells

• Wells and Tube-wells

Alternative water sources

• Rainwater harvesting

• Fog, Dew harvesting

• Reclaimed water

How much water will a system be required to deliver and to where, both today and in the future?

Domestic water consumption

• water consumption share of different micro-components (-> individual uses within the house)

• Average water consumption in Germany 111 l/(c*d)

Fluctuations in Rate of Demand

• Seasonal (Qa), daily (Qd) and hourly (Qh) variations -> an adequate quantity of water must be available to meet the peak demand

Consumption/ Peak Factors

Groundwater intake

• Vertical: shallow dug wells, tube wells, boreholes

• Horizontal: (infiltration galleries), radial collector wells, spring collection chambers

Surface water intake

• Continuous draft from streams and lakes

• River diversion -> water diverted into a channel

• Direct intake by pumping

Driking water quality criteria

• 1. Water free of disease-causing organisms

• 2. Water with harmful chemicals below defined thresholds and physical parameters within acceptable ranges

• 3. Aesthetically pleasing aspects, which is of concern to water suppliers because of consumers water safety perceptions

• 4. Water with radioactive compounds below defined thresholds

Unit Treatment Processes

Function: reduction of suspended solids load; subsequent unit treatment processes require low inflow turbities

Advantages:

• No chemicals are required

• Limited working parts and therefore robust

Disadvantages

• Requires frequent cleaning and maintenance

• Ineffective removing fine particles

Function: removal of collodial or very fine suspended particles; it affects removal efficiency of sedimentation/ granular filtration

Advantages

• Allows colloidal particles to be seperated from water

Disadvantages

• High operating costs of chemical addition

• A failure or inefficiency in the coagulation process could result in an increased microbial load entering drinking water distribution

Function: to remove coarse, coagulated, flocculated particles and to some extent harmful substances

Advantages

• Simple design and operation

Disadvantages

• Less effective to remove fine particles and bacteria

• Short-circuit currents reduce efficiency

Function: reduce the remaining suspended particles after sedimentation

Processes

• Rapid sand filtration (flow rate up to 20 m/h)

• Slow sand filtration (flow rates 0,1-0,3 m/h)

• Membrane filtration (Micro-, Ultra-, Nanofiltration, Reverse Osmosis)

Advantages

• Consistent and effective barrier for particles and pathogens

Disadvantages

• Requires frequent cleaning anf maintenance

Function:

• to inactivate waterborn pathogens

• To achieve the necessary level of microbial risk reduction

Methods

• Free Chlorine

• Combined Chlorine (Chloramines)

• Ozone

• Chlorine dioxide

• UV-Light (240-290 nm)

Disadvantages

• Disinfection by-products are produced (THMs, Bromate, Chlorite)

• Less effective against Cryptosporidium and Giardia

Pressurized pipe system

• Conservation of energy

• Resistance/ head losses

• inversely proportional

Pressure Maintenance

Periods with little consumption

• Low discharge

• Little head losses

• Filling of counter tank

Periods with high consumption

• Great discharge

• High head losses

• System input from counter tank and pump station

Piping arangements

• Primary feeders (Main pipes) (1)

• Secondary feeders (Branch) (2)

• Distributor mains (3)

Layout of Distribution Networks

• A) Dead-End System (Single Point Feed)

• B) Grid-Iron System (Branching System)

• C) Ring System (Pipe looped system)