Putting the heat on sludge

The Elimileak water meter monitoring and leak alarm system came into being

as a result of the experiences of a commercial water consumer who received a

higher than normal water bill due to the late detection of a leaking supply

pipe. Appeals to the water company to provide a means to monitor the supply

remotely or move the meter to a more convenient site met with a negative response.

The consumer felt he had identified a gap in the market and decided to investigate

whether there was any demand for a device that would enable consumers to monitor

their supplies without checking the water meter and reduce reliance on the water

company’s meter readings to identify problems.

The question arose of whether regular meter reading could help. Unless it was

carried out diligently and in conjunction with regular meter stationery tests

it was not seen as efficient, reliable or in many cases convenient. Major discrepancies

from previous readings would indicate a problem but small leaks would remain

undetected. There was also the problem of meters positioned to suit the needs

of the water company rather than the consumer.

In designing a system to tackle the problem it was recognised that pulsed meters

were available and likely to be installed in increasing numbers. This made it

possible to detect the flow of water through a meter, translate the pulses into

a readable form and use the data to perform various functions.

Two systems were suggested, hard-wired or radio link. Both would monitor pulses

from the water meter and convert them into alpha numeric form for on-screen

display. The systems would connect to the output on the water meter, with the

hard-wired version directly connected by a signal wire to its VDU while the

radio link model would transmit the data via a radio frequency to its visual

readout receiver. Both systems incorporated a dedicated microprocessor which

permitted users to select the constant flow period that best reflected their

demand expectations and triggered audible and visual alarms should these be

exceeded. The cost of the radio link version was deemed unacceptably high and

the hard-wire system was developed because it seemed, in cost terms and practicality,

to fit the requirements of the farming industry. Later it became apparent this

was the wrong option.

The hard-wired system became available in 1993 and functioned successfully,

however little account had been taken of the practical difficulties of wiring

the system to the VDU and finding a secure position for the receiver unit. The

system was limited to new-build sites where signal cables could be laid while

open trenches were available or sites where the unit could be mounted next to

the meter chamber. Sales were slow and it became clear the radio link system

was the way forward.

The electronics company which developed the system had on its own initiative

been undertaking research into a radio link option. The concept had also been

independently researched elsewhere and yet with another party on the scene Elimileak

started to move forward.

The radio link system comprised two basic units:

• a transmitter connected to the water meter capable of operating either above

  ground or within the meter chamber,

• a receiver unit capable of receiving data from the transmitter via a range

  of receiving aerials.

  The functions required of the system were:

• meter readout updated every 15 minutes or as required,
• a range of constant flow alarm settings to suit a wide variety of water user

  parameters,

• audible and visual alarms if constant flow settings are exceeded,
• transmission range up to 3-5km dependant on installation circumstances,
• user screen to enable consumers to monitor usage for any period of time selected,
• high flow alarm/selectable time period for large water consumers,
• low flow alarm/selectable time period for small users for whom monitoring

  minimum flow is critical.

South West Water agreed to co-operate at several trial sites including a shared

subsidiary office of its own. Other sites were a large Plymouth community school

and a junior school. The trials proved highly successful with the system flagging

previously undetected leaks at two of the sites within 24h of installation.

During the trials the need for several improvements became apparent. If the

transmitter was to be installed in the meter chamber up-rating of the transmitter

enclosure to an IP67 specification was essential just as the potting of all

electronic components became necessary.

Following further trials South West Water approved the product as “a valuable

aid to water management”, and permitted connection of the system to its

customers’ water meters. A recent evaluation report states: “The Elimileak

has several features which are not currently available with other products.

The meter reading screen is a useful tool and especially suitable for schools

where students can become involved in water efficiency projects and analysis.

It would also be particularly suitable for commercial customers who have long

service pipes and/or extensive underground plumbing.”

Despite the trials, as soon as the system got on to the market new problems

were encountered. It was frequently found that when the transmitter was installed

in the meter chamber it was not always possible to obtain the signals at the

preferred receiver position, and sometimes the transmission range was reduced

to as little as 50m. This problem was solved by the development of signal repeater

units. When installed near the transmission point the units relay the signals

to the receiver, using repeaters in a chain permitted almost limitless transmission

distances.

One customer wanted to link the system to a Building Management System (BMS)

which led to the creation of the Elimileak BMS interface unit. A unit capable

of monitoring combined meters was installed at the Exeter headquarters of Devon

County Council where it has been operating for more than 18 months. Commenting

on the system the council’s principal strategy and energy engineer, said: “this

instrument allows us to conveniently monitor our water consumption daily and

more importantly alarms us of any excessive consumption/leak.”

The system has proved conclusively that the scale of leakage or wasteful usage

for which the consumer is responsible is greater than statistics currently indicate.

This was best demonstrated by a contract awarded by Plymouth City Council for

26 installations at schools. In all, 15 were found to have leaks of which the

schools were completely unaware. Since installation virtually all the sites

have reported the systems have flagged leakage/wasteful usage. This has enabled

early remedial action, reducing further wastage and ensuring lower water bills.

Referring to a schools water conservation initiative, a Cornwall County Council

report concluded: “The system has certainly raised the awareness of the

value that can be gained of improved water management this even in some cases

extends to the teaching staff as well, this added benefit is attributed simply

to the ease with which monitoring can now be carried out. The existing leaks

that were detected immediately following installation of the system only confirmed

what we had previously suspected but been unable to prove and justified fully

the cost of both contracts that have been awarded.”

During the past three years those involved in Elimileak have seen commercial

water consumers taking an increasing interest in water management and as a result

the difficulties and inconvenience of carrying out frequent meter checks are

being recognised. The reliance on meters alone for water management purposes

is increasingly being questioned and new products are being demanded.