Accurate meters- Essential for water abstraction


The first abstraction licences in England and Wales were written under the terms of the Water Resources Act 1963 and were issued from 1965 onwards. From the start, all abstraction licences have carried a condition stipulating the maximum quantities of water that may be abstracted. Most also required a meter to measure the abstraction, but the conditions in the early years were vague and neither abstractors nor their regulator knew much about meters.

Clearly, an accurate meter is central to regulation of abstraction from the water environment. Nevertheless, meters have not been well understood by the officers of the Environment Agency (EA) and its predecessors, and it is only in very recent years that those who inspect abstraction sites have had adequate training in the subject.

This need to understand meters has been brought about in part because the relationship between abstractors and the regulator has changed. Prior to 2001, the EA used to send inspectors to all the sites at which it authorised a discharge into and/or an abstraction from the environment. Now, more responsibility lies with licence holders to ensure they are observing the conditions of their licences.

Of course, the Agency does still send inspectors to check licences, but priority is given to abstractions where the environment requires special protection, or where there is a known problem. Many abstractions do not fall into either of these categories and, even when a licence authorises a very large abstraction, the licence holder is expected to record and return its own data. It is essential for the Environment Agency to have confidence in the source of that data if its officers are visiting less frequently.

Until October 2001, most abstraction licences in England and Wales were issued ‘in perpetuity’. What is more, the Environment Agency has never been empowered to revoke a licence, except for non-payment of charges. This is still true, but now all new licences, and many that are varied at the holders’ request, are time-limited. To sweeten the pill, licensees have been told there will be a presumption of renewal provided that:

  1. The abstractor can show continuing need. A record of abstraction over several years by means of an accurate meter will be an integral part of the evidence.
  2. The EA remains confident that there are sufficient water resources. Calculations will include the total metered returns received from all licence holders in the catchment.
  3. The abstractor can show that the abstracted water is being used efficiently. Exact details of what will be required have yet to be formally communicated, but it is certain that accurate meter records will be an essential part of any submission.

Naturally, these conditions apply equally to the water companies who abstract from groundwater and watercourses for public supply. They are among the largest of the Environment Agency’s abstractors and operate licences with some extremely complex conditions.

Most licences written in the last decade have included a condition requiring that the meter is kept in good working order. However, the EA is not certain that some of the largest abstractors, such as water companies, have records to show how their meters were installed or are being maintained. If the installation is incorrect or the meter has not been flow checked regularly, there is a strong possibility that it could be under- or over-recording. While small businesses such as farms have meters that can be seen and checked relatively easily, the really large abstractions, with appropriately large meters, pose a more difficult problem. If they have a meter-checking schedule, then the EA would appreciate details; if they do not, then there is an urgent need to discuss how such a regime can be put in place.


A ‘Metering Good Practice Manual’ was first published by the Environment Agency in 1997. The document was approved after consultation with many abstractors, including water companies. While the manual recognises that not all abstractions can be metered, it stresses the Agency’s policy that in a very large majority of cases a meter can and should be the chosen method of measuring the water abstracted. The manual only addresses abstractions from closed pipes, but gives valuable guidance about which type of meter is suitable for different sizes of pipe and purpose. It has been updated several times and is the Agency’s principal source of help to abstractors.
The practice of burying meters rather than constructing inspection chambers for them has come under the spotlight recently – and not for the first time. Water companies in particular found some years ago that it was cheaper to bury a meter. Since then, however, the companies are finding that the reliability of buried meters has suffered. Having to disinter meters when they fail is costing a lot more than construction of the inspection chambers would have cost originally.

Figure 1: Checking the accuracy of water meters in situ

Figure 1: Checking the accuracy of water meters in situ

Figure 2: Traceability is the key to all actions with secure archiving & retrieval

Figure 2: Traceability is the key to all actions with secure archiving & retrieval

When the practice first came to the attention of the Environment Agency some years ago, it warned against burial of abstraction meters for all the reasons that have now come to light. It will now benefit both the companies and the Agency to talk about how to install abstraction meters in a way that satisfies both parties. It is essential that these more complex abstractions can be checked by some means that both the company and the Agency can feel confident about. Environment Agency inspectors do not all have water resources expertise, particularly when faced with electromagnetic or similar meters that are the chosen instruments of large abstractors.

In order to protect the environment while placing more responsibility on those whose operations have the potential to damage it, the EA started to look at how all meters, their installations and those who installed them, could be certificated to an agreed standard. A group was set up to establish these standards, and the system is now known as the Environment Agency’s Monitoring Certification Scheme (MCERTS).

An independent company with the expertise to check all three elements on behalf of the Environment Agency certifies acceptance of the instruments, installation and installers. To date, water abstraction installations have not been included in the MCERTS schedules. That may be about to change.

A new software system has been produced to check the accuracy of water meters in situ. It works on the principle that meter verification requires not only a check of the flow meter itself, but also the effects of the installation on the meter’s performance. So the layout of the meter installation and pipework, all upstream and downstream disturbances and details of pipe condition and earthing are all included in the site survey. (See Figure 1).

Because it is essential to know these details, the system uses actual data where it is known, and substitutes default figures for data which is not known. The result is an uncertainty figure for the meter and its installation as a whole. The advantage of this system is that it retains the results of all the tests and therefore provides an audit trail of how the final figure was achieved. In future, this data can be stored in whatever way the regulator and companies agree. (See Figure 2).


The Environment Agency and the abstractors using the system will have to agree a level at which an uncertainty figure is unsatisfactory for any particular meter. While it is envisaged that there will be several levels between fully satisfactory and totally unreliable, it should be recognised that an unsatisfactory result will not necessarily mean that the meter is not recording accurately. It might be that lack of knowledge of the installation has caused a number of ‘unknowns’ to be included in the program where substitution of actual data would have produced a fully satisfactory result. Once the software program is certified by MCERTS, abstractors whose meters may be difficult or impossible to access will have the option to adopt the system if they do not already have a maintenance schedule.

Once the installation of a meter has been checked by means of known records or by a computer program as described in the last paragraph, the data on intrinsic water meter performance can be obtained from an insertion probe or from proprietary verification instruments. However, while insertion probes are a tried and tested method of checking meters, the Environment Agency is likely to accept the results of a verification instrument only if it has been submitted for field and laboratory testing to the Agency’s own standards. Currently only one model has passed this test satisfactorily.

At the time of going to press, the south east of England is bracing itself for a drought during the summer of 2005. The media has already been primed to warn the public to expect hosepipe bans and possible loss of automatic car washes and similar non-essential uses of mains supply water. Among agricultural abstractors, spray irrigators may have to forego a proportion of their authorised quantities.

If the situation does become critical, water companies which have applied bans on hosepipes and other non-essential uses of water will be given leave to apply for Drought Orders. These are issued by the EA and allow the companies to abstract from rivers below the flow rate at which they would normally be required to stop (the ‘Hands Off Flow’ rate). This will have a significant effect on the environment in and around rivers, and will attract attention from many sections of the public. The companies and the Environment Agency will need to be confident in the data that the abstraction meters are giving in such controversial circumstances.

This is not an isolated event. The general belief is that climate change is happening and dry summers are going to be much more common. It will be even more essential in the future that meters for recording all water abstractions are reliable and accurate. Those that record summer abstractions will be under particular scrutiny.