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How to get your allowances accurate
Licensed plumbers need to understand our requirements when they take measurements for installing light or heavy duty water meters. The distance allowed between the pipes depends on the size of the meter. Measurements must be accurate. They help us to safely read, maintain and exchange meters in the future.
20 mm to 50 mm light duty meters
You need to measure between the ends of the threads to work out the distance needed to allow for these light duty meters. The arrows on the image show where to start and finish measuring.
Once you've done this, use the measurements below to work out your distance.
The arrows show where to start and finish measuring.
| Meter size (DN) – drinking water | Distance to allow – drinking water |
|---|---|
20 mm |
260 mm |
25 mm |
310 mm |
32 mm |
350 mm* |
40 mm |
350 mm* |
50 mm light duty |
340 mm* |
The right-angle stop valve and elbow have male BSP threads. |
* This doesn't include the distance for the backflow prevention device. |
| Meter size (DN) – recycled water | Distance to allow – recycled water |
|---|---|
20 mm |
270 mm |
25 mm |
265 mm |
The right-angle stop valve has a female BSP thread. |
The elbow has a female BSP thread. |
You need to allow a minimum of 300 mm clearance around light duty meters. This helps us to safely read, maintain and exchange them in the future.
When you have your distance right, you need to insert a bridging piece where the meter will go. We'll remove the bridging piece when we install the meter.
The bridging piece
Insert the bridging piece where the meter will go. We'll remove it when we install the meter.
A correctly installed meter
If everything is done correctly, we won't have any problems installing a meter later on.
50 mm to 300 mm heavy duty meters
To work out the distance required for heavy duty meters, measure between the flange ends. Flange ends have flat surfaces instead of threaded ones.
Heavy duty meters have extra parts. These must also be allowed for.
Use these measurements to work out your distance.
| Meter size | Gate valve | Dirt box | Distance piece inlet | Meter | Distance piece outlet | Meter assembly space |
|---|---|---|---|---|---|---|
50 mm heavy duty |
175 mm |
208 mm |
372 mm |
311 mm |
150 mm |
1,216 mm |
80 mm |
203 mm |
252 mm |
396 mm |
413 mm |
240 mm |
1,504 mm |
100 mm |
229 mm |
260 mm |
476 mm |
483 mm |
300 mm |
1,748 mm |
150 mm |
267 mm |
406 mm |
762 mm |
500 mm |
450 mm |
2,385 mm |
200 mm |
292 mm |
428 mm |
1,000 mm |
520 mm |
600 mm |
2,840 mm |
250 mm |
330 mm |
522 mm |
1,250 mm |
450 mm |
750 mm |
3,302 mm |
300 mm |
356 mm |
580 mm |
1,500 mm |
500 mm |
900 mm |
3,836 mm |
You must allow a minimum of 500 mm clearance around these meters. This is so we can exchange them in future.