Minimum night flow (MNF) analysis was carried out in the PSA. The MNF of the PSA was around 87 m3/h before water loss control studies started. As active leakage control studies were implemented in June 2020, the MNF value started to decrease down to 76 m3/h. Then an increase was observed in MNF rates as new bursts occurred. In the meantime, active and passive leakage control studies were carried out and a water meter replacement campaign was started. As water distribution systems are dynamic systems, active and passive leakage control studies should be carried out regularly. At the end of the study period, MNF rates of the PSA were observed around 65 m3/h. Average MNF rates before the studies started were around 87 m3/h whereas average MNF rates were reduced up to 65 m3/h. An average water saving of 22 m3/h was achieved by implementing active and passive leakage control and the water meter replacement campaign. The rate of water losses has been reduced from 52% down to 35% by implementing integrated water loss management strategies. Standard water balance tables of the PSA are presented in Tables 3 and 4. Unbilled unmetered consumption is the water that is connected to the network by the water administration but is not metered and therefore not billed within the knowledge of the administration. It basically consists of the amount of water used from parks, fire hydrants, water discharged during the maintenance of pipelines and armatures etc.
Standard water balance of the PSA before study (for 11 months)
| System input volume (SIV) 139,734 m3/year 100% | Authorized consumption (AC) 412,648 m3/year 48.47% | Billed authorized consumption 404,063 m3/year 47.46% | Billed metered consumption 404,063 m3/year 47.46% | Revenue water 404,063 m3/year 47.46% |
| Billed unmetered consumption 0 m3/year 0.00% | ||||
| Unbilled authorized consumption (UAC) 8585 m3/year 1.01% | Unbilled metered consumption 220 m3/year 0.03% | Non-revenue water (NRW) 447,347 m3/year 52.54% | ||
| Unbilled unmetered consumption 8365 m3/year 0.98% | ||||
| Water losses 438,762 m3/year 51.53% | Apparent losses (AL) 145,080 m3/year 17.04% | Unauthorized consumption 21,285 m3/year 2.50% | ||
| Metering inaccuracies 123,794 m3/year 14.54% | ||||
| Real losses (RL) 293,682 m3/year 34.49% | Leakage on transmission and/or distribution mains 289,295 m3/year 33.98% | |||
| Leakage and overflows at utility's storage tanks 4388 m3/year 0.52% |
| System input volume (SIV) 139,734 m3/year 100% | Authorized consumption (AC) 412,648 m3/year 48.47% | Billed authorized consumption 404,063 m3/year 47.46% | Billed metered consumption 404,063 m3/year 47.46% | Revenue water 404,063 m3/year 47.46% |
| Billed unmetered consumption 0 m3/year 0.00% | ||||
| Unbilled authorized consumption (UAC) 8585 m3/year 1.01% | Unbilled metered consumption 220 m3/year 0.03% | Non-revenue water (NRW) 447,347 m3/year 52.54% | ||
| Unbilled unmetered consumption 8365 m3/year 0.98% | ||||
| Water losses 438,762 m3/year 51.53% | Apparent losses (AL) 145,080 m3/year 17.04% | Unauthorized consumption 21,285 m3/year 2.50% | ||
| Metering inaccuracies 123,794 m3/year 14.54% | ||||
| Real losses (RL) 293,682 m3/year 34.49% | Leakage on transmission and/or distribution mains 289,295 m3/year 33.98% | |||
| Leakage and overflows at utility's storage tanks 4388 m3/year 0.52% |
Standard water balance of the PSA after study (for two months)
| System input volume (SIV) 139,734 m3/year 100% | Authorized consumption (AC) 90,295 m3/year 64.62% | Billed authorized consumption 88,734 m3/year 63.50% | Billed metered consumption 88,734 m3/year 63.50% | Revenue water 88,734 m3/year 63.50% |
| Billed unmetered consumption 0 m3/year 0.00% | ||||
| Unbilled authorized consumption (UAC) 1561 m3/year 1.12% | Unbilled metered consumption 40 m3/year 0.03% | Non-revenue water (NRW) 51,000 m3/year 36.50% | ||
| Unbilled unmetered consumption 1521 m3/year 1.09% | ||||
| Water losses 49,439 m3/year 35.38% | Apparent losses (AL) 12,523 m3/year 8.96% | Unauthorized consumption 3493 m3/year 2.50% | ||
| Metering inaccuracies 9029 m3/year 6.46% | ||||
| Real losses (RL) 39,919 m3/year 26.42% | Leakage on transmission and/or distribution mains 36,422 m3/year 26.07% | |||
| Leakage and overflows at utility's storage tanks 494 m3/year 0.35% |
| System input volume (SIV) 139,734 m3/year 100% | Authorized consumption (AC) 90,295 m3/year 64.62% | Billed authorized consumption 88,734 m3/year 63.50% | Billed metered consumption 88,734 m3/year 63.50% | Revenue water 88,734 m3/year 63.50% |
| Billed unmetered consumption 0 m3/year 0.00% | ||||
| Unbilled authorized consumption (UAC) 1561 m3/year 1.12% | Unbilled metered consumption 40 m3/year 0.03% | Non-revenue water (NRW) 51,000 m3/year 36.50% | ||
| Unbilled unmetered consumption 1521 m3/year 1.09% | ||||
| Water losses 49,439 m3/year 35.38% | Apparent losses (AL) 12,523 m3/year 8.96% | Unauthorized consumption 3493 m3/year 2.50% | ||
| Metering inaccuracies 9029 m3/year 6.46% | ||||
| Real losses (RL) 39,919 m3/year 26.42% | Leakage on transmission and/or distribution mains 36,422 m3/year 26.07% | |||
| Leakage and overflows at utility's storage tanks 494 m3/year 0.35% |