Separating supply pipe leakage from plumbing losses

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1 Separating supply pipe leakage from plumbing losses Steve Tooms

2 Supply pipe leakage and plumbing losses Whats the problem? Total leakage includes underground supply pipe leakage. Plumbing losses are part of consumption. The boundary between underground supply pipe leakage and consumption is not well defined Does it matter? If plumbing loss estimate is too low leakage is overestimated consumption is underestimated leakage ODIs, water efficiency ODIs

3 What s the problem?

4 Total Leakage What is included? Trunk main losses Service reservoir losses Distribution main losses Communication pipe losses Boundary box losses Underground supply pipes losses What is not included? Plumbing losses: Overflowing toilets Leaking toilet flap valves Dripping taps Plumbing leaks Use, including: Ball-valve tails Low flow trickle devices

5 Leakage vs Continuous Consumption: how is the boundary decided? Operationally Acoustic detection Meter readings Close the external/internal stop tap, check noise and meter For reporting For most sampled companies in : BABE with the original (1994) assumptions: background is a major contributor to this. Reported bursts and leaks Unreported bursts and leaks Background leakage

6 BABE: Background estimates in 1994 Tests in to find lowest achievable leakage in DMAs after intensive detection and apportion between mains, CPs, and private side Private side split, with minimal evidence 50/50 to underground supply pipe and plumbing losses! Communication pipe 3 l/hr Background in total losses 3.5 l/hr Underground supply pipe 0.5 l/hr Background losses on a customer connection Plumbing 0.5 l/hr Background in plumbing losses 0.5 l.hr

7 BABE: background assumptions in 1994 Communication pipe 3 l/hr Underground supply pipe 0.5 l/hr Plumbing 0.5 l/hr Background in total losses 3.5 l/hr Background in plumbing losses 0.5 l.hr Background losses on a customer connection

8 BABE: Its legacy now CP background losses: Re-assessed as typically 2 l/hr Beyond the boundary 1 l/hr May be used in estimating targets and (SELL) Supply pipe leakage or plumbing losses? 1 l/hr of uncertainty in total losses

9 Only 1 l/hr of uncertainty 22 litres/property/day 25% of typical leakage target Affects leakage ODI and water efficiency ODI

10 Features of background leakage Impossible to find Highly correlated with the number of properties in a DMA Small leaks Very pressure dependent flow rate (N1>1)

11 Where is the background leakage? Where are the small leaks, where are the flexible materials, where is the pressure-flow dependence high? Internal stop tap Ferrule Customer meter Main

12 Evidence: individual household monitor* * Internally metered

13 Evidence: IHMs end of continuous flow with no supply pipe repair* * Externally metered

14 Conclusions from work last year Continuous consumption (plumbing losses + use) at least 0.8 l/prop/hr (unmeasured) Best estimate of continuous consumption (plumbing loss + use) >1.3 l/prop/hr. Implication: total leakage may be 20 l/prop/day less than reported in some companies. Small number of properties with medium flows over a long period have a big impact

15 Further work

16 Flow into an unmeasured property using a new technique

17 Flow into an unmeasured property (with continuous flow)

18 Diurnal flow pattern for a group of properties

19 Night flows to a set of unmeasured properties by a new technique

21 Conclusions Plumbing losses and continuous use are probably higher than typically estimated: total leakage is probably lower than reported. More research is needed to quantify plumbing losses more effectively. New sensor techniques provide an opportunity to assess the pattern of flow into individual properties. Benefits for plumbing loss assessment, night use assessment, leak detection, occupancy assessment Long term implications are significant. If leakage is already lower than targets, what happens to ODI payments/penalties?

22 Thank you Steve Tooms Invenio Systems

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