Water efficiency: a step by step guide

Reducing water use saves money, can enhance the reputation of a business and preserves natural resources. But where should a business start? This guide will help your business through the first stages of setting up a water efficiency strategy.

Water as a Resource

Water is often taken for granted: You turn on a tap, and as if by magic, it is there. However, water is a resource like any other, and hence its supply should be treated with respect.

As such, all businesses should make sure that their operations are as water efficient as possible.

The benefits are clear:

  • Save money
  • Save carbon emissions
  • Protect the wider environment
  • Avoid potentially damaging leaks

This document provides a first step for businesses wishing to use water wisely, and achieve water efficiency in their organisation. It is supplemented by the following further Water Efficiency Guidance documents in the our Information Pack:

  • Billing
  • The Open Water Market
  • Behaviour Change
  • Site Walkthrough Checklist

The Water Management Hierarchy

The Water Management Hierarchy is a framework for prioritising water management and efficiency actions.

Keep the waste hierarchy in mind when undertaking water savings actions: those which deliver results closer to the top of the hierarchy should be preferred.

The Water Management Hierarchy: What should you consider?

Reduce costs and eliminate water waste to enjoy greater savings for your business

The water management hierarchy

Top Tip

A good water balance model, which accounts for at least 90% of your billed water consumption, will serve as a tool to understand and manage water use.

Step 1: Understand your water use

Once you have committed to begin saving water, the first step is to understand how water is used in your business. This should be started by asking the following questions:

  • How is mains water supplied to site?
  • Is there one or multiple supplies?
  • Is there any alternative water supplies?
  • How is water disposed of after use?
  • Do you discharge wastewater (sewerage and trade effluent)to sewer and/or controlled water (river, stream, etc.)
  • Where is water used in your business (domestic use, process use, inside and outside)?

The final question will be key to improving your water efficiency. Typical water use areas for businesses include:

  • Toilets and urinals
  • Cooling water
  • Washing hands
  • Hot water/steam boilers
  • Use in products (Ingredient)
  • Drinking water fountains
  • Rinsing products
  • Washing vehicles
  • Watering landscaped areas
  • Machine lubrication

A simple and effective tool for understanding your water use is a water balance model. Water balance models numerically account for:

  • How water enters the site (mains water, other sources)
  • How water is used within the site
  • How water exits the site (sewer discharge, trade effluent)

The following steps outline how you can produce a water balance:

  • Gather existing data on water use and costs (e.g. water, sewerage and trade effluent bills)
  • Identify the main water using activities, and try to quantify them (measure flows, manufactures data, rules of thumb such as 25 I/person/day for domestic amenities in sites with no canteen)
  • Identify where existing water meters and sub meters exist to assist in quantifying flows to different areas
  • Bring this information together in a simple spreadsheet or in a block diagram to develop the water balance (example below)

One of the main benefits of a water mass balance is to identify any unexplained water consumption, such as leaky pipes.

Water balance model

Water balance model

Did you know?

A dripping tap can waste more than 60 litres of water a week?
That’s the same as 39 bath tubs of water a year.

Step 2: Set Key Performance Indicators

Measuring water efficiency performance over different time periods helps to gain a better understanding of how your business uses water and where efficiencies can be made. This is best done through setting water management key performance indicators (KPls), which are water use targets proportional to an applicable variable site activity indicator (such as production levels).

KPls allow a business to:

  • Establish baseline water efficiency performance
  • Track changes in efficiency over time
  • Compare your water use to published  benchmarks for your industry

Typical KPl’s for water management include the following:

  • Water Use: m3 per employee / site occupant or tonne of product/m3
  • Effluent Strength: kg Chemical (or Biochemical)
  • Oxygen Demand per tonne  of product

A key part of using KPls as effectively as possible is to analyse them graphically, in order to visualise if they remain steady, increase or decrease over time. Also, high variation in a KPI graph can illustrate poor control over water use levels. An example of such a graphical analysis is below.

Water Use KPIs

Good Idea

While final savings numbers depend on the site in question, Castle Water’s experience suggests a robust Water Efficiency Action Plan can save up to 50% of a site’s water related consumption and costs.

Step 3: Water efficiency action plan

Once the water balance has been constructed and a baseline water efficiency established by setting KPl’s, the goal is of course to improve performance.

There are many water saving techniques, so prioritisation is key, according to factors such as:

  • The budget available for investment
  • The water savings possible through each action
  • Operational costs of any technology solutions
  • Prioritising hot water savings (heating one m3 of water to 75°C can cost over £7)

A general list of potential water efficiency technologies is presented over the page. Some of these (particularly urinals, taps, and toilets) will be universally applicable.

However, others (particularly those regarding process water use) will be site specific. In order to tap into these (which depending on the site in question can deliver the most savings), advice can be sought from:

  • A water retailer such as Castle Water
  • Environmental consultants
  • Technology suppliers

Leakage is a key area which should be addressed (if identified by a water balance model) in any effective Water Efficiency Action Plan. The water and costs savings possible through remediating even simple leaks are shown below:

Top Tip

More complex sites can benefit from expert consultancy support for water efficiency. Castle Water is in a position to provide this to its customers.

See our additional services

Step 4: Consider alternative water sources

Alternative water sources represent a different option to mains water. They are typically used for applications for which water treated to a high quality is not needed, including flushing toilets and urinals, grounds irrigation, and various process uses.

Alternative water sources include:

  • Rain and stormwater
    Water runoff from roofs or ground areas collected and stored for reuse
  • Boreholes
    Wells drilled to allow access to underground water sources
  • Surface water
    Water sourced from rivers,  streams, etc.
  • Reclaimed water
    Water which has already been used in onsite processes, and is reclaimed for reuse

There are multiple potential benefits of using alternative water sources. These include saving money (through reduced mains water bills) and a reduced environmental impact (by using water which is only treated to the necessary quality, and hence results in lower treatment based carbon emissions). However, they must be properly managed to ensure their safe use.

With this in mind, two British Standards are available for reference regarding the implementation and operation of different alternative water sources. These are:

  • 858515:2009 for rainwater harvesting systems
  • 858525-1:2010 for greywater systems

Did you know?

Installing a hippo cistern displacement device in your toilet cistern can save you up to 3 litres water per flush?

Step 5: Drive continual improvement

Steps 1 to 4 of this guide provide the basics for a SME who wishes to improve their water efficiency - and save money and improve environmental performance in the process.

However, water efficiency should be seen as a continual process, in which improvements are monitored and continuous improvement driven.

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