Water Audit Basics
Types of Water Audits
- Supply-Side (system-wide) audit
- Analysis of a water agency’s billing, metering,
maintenance and operational practices that may contribute to loss of water or revenue
- Onsite (customer) audit
- Analysis of water usage by residential, commercial,
industrial and institutional customers that contribute to conservation… or waste
Water Audits
- Water in:
- Groundwater/surface water
- Purchased water
- Total water in____________
- Water out:
- Metered
- Leaks/theft/under billing/ faulty control systems
- Total water out___________
- Water in – water out = “unaccounted-for” water
Benefits Of Water Audits
- Financial
- Recovery of revenues from undercharged
customers
- Recovery of billable product from stopping leaks
- Less wholesale water to purchase
- Reduced treatment and pumping costs
- Reduced potential for damage to public and
private property
- Increased understanding of distribution system
- Increased familiarity with physical components of
distribution system
- Increased experience with agency’s mapping system
- Verification of mapping data
- Decreased response time for emergencies and
broken mains
- Efficient use of existing supplies
- Stretch existing supplies to meet increased needs
- Deferred construction of new facilities
- New wells
- New reservoirs
- Treatment plant expansion
- Wastewater plant expansion
- Reduced Liability Exposure
- Demonstrates “Due Diligence”
- Decreased likelihood of property damage from rupture of undetected leaks
- Decreased likelihood of contamination during low pressure events
Public Relations Opportunities
- Demonstrates proactive management
- Helps justify mandatory conservation/restrictions
- Produce informational materials to explain and
educate
- Give to field crews
- Send to news media
Supply Side Audits
What Is The Cost Of A Water Audit?
Depends on….
- Size of the service area
- Completeness and accuracy of in-house record
keeping
- Meter testing programs
- Whether in-house or by consultants
- Information on hand,
- system complexity and
- other variables
Water Audit Activities
Verifying, Quantifying and Updating:
- Water source inflow records
- Inaccurate source data will invalidate the audit
- Billing and accounting information
- Unmetered use records
- Parks,
- community centers,
- government facilities,
- firefighting
- Verifying and Updating system maps
- Master and source meter accuracy
- Testing residential, commercial, and industrial sales
meters for accuracy
- Large meter testing is often the most expensive
item of a water audit
- £100-£300 per meter
- If repair needed - additional £200-£700
Authorised Unmetered Use
Unmetered uses must be carefully estimated to produce an accurate
audit
All water users should be metered even if not billed!
Causes of Meter Error
- Age (internal wear)
- Improper type of meter for application
- Improperly sized
- Improperly installed (backwards; sloping; insufficient distance from valves &
fittings)
- Registers not installed correctly
- Hard water encrustations
- Mineral deposits
Meter Testing Alternatives
- Test in place
- Modification of piping may be required
- Install a calibrated meter in series with original
meter and compare readings
- Record flow over a specified time; replace it with a
calibrated meter over the same time period and compare readings
- Remove the meter and test at a meter testing facility
Customer-Side Water Audits
Indoor Water Use
For single family homes, average water use/person = 69.3 gallons, 129
litres per day
Indoor Water Use
| Use |
Gallons/capita |
Litres/capita |
% of total |
| Showers |
11.6 |
20 |
16.8% |
| Clothes washers |
15.0 |
26 |
21.7% |
| Dishwashers |
1.0 |
1.75 |
1.4% |
| Toilets |
18.5 |
32.5 |
26.7% |
| Baths |
1.2 |
2.1 |
1.7% |
| Leaks |
9.5 |
16.7 |
13.7% |
| Faucets |
10.9 |
19 |
15.7% |
| Other |
1.6 |
2.8 |
2.2% |
Water Conserving Fixtures
Using these features reduces daily consumption to 42 Gallons/person/day or 74
litres/person/day
| Use |
Gallons/capita |
Litres/capita |
% of total |
| Showers |
8.8 |
15.5 |
19.5 |
| Clothes washers |
10.0 |
17.5 |
21.7% |
| Dishwashers |
0.7 |
1.23 |
1.5% |
| Toilets |
8.2 |
14.4 |
18% |
| Baths |
1.2 |
2.1 |
2.7% |
| Leaks |
4.0 |
7.0 |
8.8% |
| Faucets |
10.8 |
19 |
23.9% |
| Other |
1.6 |
2.8 |
3.4% |
Indoor Water Use Efficiency
- 1984 77 gpc
- 1999 69 gpc
- Potential 42 gpc
- 1992 US Energy policy act mandated maximum flows for toilets,
urinals, showerheads & faucets
- Now part of National Plumbing Code
Fixture History
Toilets
| 1970’s |
7+ gallons/flush (g/f) |
12+ litres/flush
(l/f) |
| 1980’s |
3.5 – 5 g/f |
6 - 8.8 l/f |
| 1992 |
1.6 gpf (Nat’l
Plumbing Code) |
2.8 l/f |
| 2000’s |
1.28 gpf (High
Efficiency Toilets) |
2.25 l/f |
Showerheads
| 1970’s – 80’s |
3.5 gallon per minute
(g/m) |
6.15 litres per minute (l/m) |
| 1992 |
2.5 g/m |
4.4 l/m |
Faucets
| 1970’s – 80’s |
3 + g/m |
5.3 l/m |
| 1992 |
2.2 g/m |
3.87 l/m |
Urinals
P
| re 1992 |
2 to 4 + g/f |
3.5 - 7 + l/m |
| 1992 |
1 g/f |
1.76 l/m |
Factors Influencing Residential Water Use
- Age of home (fixtures)
- Leak losses
- Climate
- Number of occupants
- Wasteful practices
- Irrigation practices
- Pool/spa
- Lot size
Commercial, Industrial, and Institutional (CII) Water
Use
- Wide variety of non-residential customers
- Wide range of water use characteristics
- Ratio of CII to non-residential demand varies by community
- Conservation measures must targeted to individual CII customers
Commercial, Industrial, and Institutional (CII) Customers
- Offices
- Restaurants
- Microbreweries
- Schools
- Shops/stores
- Factories
- Parks/greenbelts
Commercial, Industrial, and Institutional (CII) Water
Uses
- Domestic uses (sinks, toilets, urinals)
- Spray wash rinse valves (restaurants)
- Landscape irrigation
- Cooling towers/boilers
- Process washing/rinsing (factories, breweries)
- Pulp/paper production
Overview Of Recommended Technologies
- High Efficiency Toilets (HET)
- Dual flush handles
- Pint flush urinals
- Waterless urinals
- Faucet aerators
- Low-flow showerheads
- Alternative mechanical systems
Goals Of A Customer-Side Water Audit
- Determine cost-effective conservation options
- Prioritize retrofits
- Save water, sewer and costs
- Save pumping (electricity) costs
- Reduced chemical usage
Customer-Side Water Audits
- Where is water being used?
- How much is being used?
- How much does the water & sewage cost?
- What are the water savings/cost potential?
- Will there be additional savings?
- Less heated water?
- Less pumping?
Data Collection
- Obtain two years (optimal) of water and wastewater usage records
- List all water using equipment
- Obtain water use characteristics of fixtures
- Estimate frequency of use
- Determine irrigation use and schedule
Identify Fixture Characteristics
- Toilets - g/m l/m
- Showerheads - g/m l/m
Lavatories - g/m l/m
Washing machines – Gallons per cycle (g/c) Litres per cycle (l/c)
Dishwashers – g/c or l/c
Kitchen facilities – spray nozzles/other
Irrigation – g/p or l/m plus cycle durations
Misc. – ice maker, steamers,
Additional Information
- Annual water consumption
- Utility & sewer rates
- Floor plans to identify number of fixtures
- Walk through audit – identify fixture characteristics
and useage
- Occupancy rates / visitors
- Hours of use of equipment
Water Conservation Measures
- Utility side
- Water system audit (universal metering)
- Leak detection and repair program
- Volumetric pricing
- Water waste prohibitions
- Financial incentives
- Toilets
- Washing machines
- Free showerheads, toilet seal kits, tank
displacement bags, aerators, etc
- Customer side
- Residential water audits
- Performed by customer
- Performed by utility
- CII water audits
- Retrofit fixtures/equipment
- Change behavior/procedures
- Customer outreach
- School educational programs
- “Recycled” water
CII Conservation Measures
- Urinal retrofit (waterless)
- Pressure assisted toilet retrofit
- Clothes washer retrofit (laundries)
- Showerhead retrofit (hotels, schools, retirement
homes)
- Weather based irrigation controllers
- Cooling tower process changes (single pass)
Conservation Incentives - Through Rate Structuring
- Flat fee
- Uniform rate
- Decreasing block rate
- Increasing block rate
- Seasonal rates
Which Water Rate Is Best For Your System?
Consider:
- Customer use uniformity
- Availability of supply vs. demand
- Cost of water production
- Community development
- Water rights
- Fairness to customers
Leak Detection
Distribution System Leaks
- 6 billion gallons lost in U.S.each day!
- 228 billion gal. per year in CA alone
- Average of 10% of all water produced in CA is lost to
leakage (Range: <5% to >30%)
So What’s The Problem?
- $340 million per year in lost revenue to CA systems
- $170 million in emergency overtime labor & equipment
- Bottom Line: Over half a billion $$$ in costs to CA
water systems alone!
- >50% of these costs are preventable
Why Do Distribution Systems Leak?
- Age
- Corrosion
- Faulty installation
- Material defect
- Excessive pressures (or surges)
- Ground movement
- Traffic loading and vibration
Where Is All This Water Going?
Leaks follow the path of least resistance
- Porous (sandy) soil
- Gravel backfill
- Sanitary sewers
- Storm sewers
- Geologic features
- A few actually reach the surface!
Leak Detection Technology
- Portable contact (probe) devices
- Unpowered geophones (stethoscope)
- Amplified acoustic microphone systems
- Multi-channel acoustic correlators
- Portable noise loggers
What Do Leaks Sound Like?
- Always present – a “hiss” or “whoosh” sound
- Splashing or “babbling brook” noises
- Rapid beating/thumping from spray hitting wall of the cavity
- “Clinking” sounds of stones and pebbles bouncing off of
pipe
Typical Equipment Cost
- Portable contact (probe) devices - $1500-$2000
- Unpowered geophones - $30-$350
- Amplified acoustic detection systems - $2500-$3800
- Multi-channel acoustic correlators - $17,000 - $23,000
- Portable leak noise loggers - $200-$600 per unit depending on quantity
Equipment options
- Purchase (good investment)
- Rent / Lease
- Hire a contractor
- CRWA
- Borrow from neighboring agency
- Vendor demo units
Justifying The Cost Of Leak Detection Programs
- Leaks get worse with age
- Leaks increase the likelihood of system contamination
- Leaks damage public and private property
- Reduced liability exposure
- Improved public relations
- Improved knowledge & documentation of distribution system
- More efficient use of source capacity
- Reduced disruption to customers
- Safeguard public health!
How Is A Leak Survey Done?
- Map out a grid of water system
- Experienced crew should cover 6 to 8 miles per day
- Conduct preliminary survey using contact (probe)
equipment
- Return to pinpoint suspected leak locations using correlation
Getting Started
- Public education
- Personnel w/ photo ID
- Vehicle(s)
- Equipment
- Don’t forget traffic safety devices!
- Good maps and plans
Resources
For more information contact
Mearsecroft
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