Water System Analysis

Challenge

The client manages the Aloe Ridge development, a large multi‑village estate. By 2024 they were facing:

• Significant, expensive water losse from the water network
• Ageing, Class 6 pipework with limited bedding quality
• Outdated or incomplete as‑built drawings
• Uncertainty about whether to repair, pressure‑manage or fully replace key systems

CCH needed hard data to guide multi‑million‑rand decisions, rather than relying on assumptions.

Our Brief

African Crake Projects (Pty) Ltd, supported by Ant Consult, was appointed to undertake a full hydraulic investigation of Aloe Ridge Villages 1 and 2, supported by detailed network mapping and modelling.

The objectives were to:

1. Rebuild accurate as‑builts for potable, fire, sewer and stormwater networks
2. Quantify real water losses and distinguish leakage from legitimate consumption
3. Locate critical leaks and weaknesses in the fire and potable systems
4. Recommend practical interventions – from quick wins to full system renewal – with cost estimates for budgeting

What We Did

1. Ground‑truthing and mapping

• Multiple site visits with targeted excavation to prove pipe sizes, alignments and classes
• Identification of all valves, meters, fire hydrants, scours and air valves
• Capture of the full potable water, fire water, sewer and stormwater network in a geo‑referenced GIS database and PDF as‑built drawings, now used by CCH as its primary record.

2. Monitoring and hydraulic modelling

• Flow logging on bulk meters for both villages
• Pressure logging at strategic locations on potable and fire systems
• Construction and calibration of detailed Civil Designer / EPANET models
• Side‑by‑side comparison of modelled vs measured behaviour to pinpoint:
  • Systemic leakage
  • Localised faults
  • Unmetered connections and bypasses
  • Over‑pressure and partially closed valves

Key Insights

Village 1 – High losses and structural issues

• Discovered and closed an unmetered Ø250 mm bypass between Villages 1 and 2, restoring proper metering.
• Confirmed no unwanted municipal or fire‑potable interconnections, focusing attention inside the village network.
• Quantified leakage:
  • Fire system baseflow ≈ 0.5 l/s plus daytime peaks from domestic use of fire lines
  • Potable system leakage ≈ 1.7 l/s – about 49% of average inflow
• Identified hotspot leak zones by finding areas of localized low pressures
• Documented excessive pressures on low‑class pipe:
  • Potable pressures up to 120 m (12 bar) on Class 6 (60 m) mains
  • Modelled fire system pressures up to 118 m
• Produced a detailed replacement cost estimate for fire and potable water systems.

Village 2 – Sound network, over‑pressurised

• Demonstrated minimal systemic leakage:
  • Potable baseflow at bulk meters close to zero
  • Fire system night flows approaching zero
• Showed that peaks on the fire system were due to intermittent domestic use, not continuous leaks.
• Flagged local risk areas.
• Confirmed that both potable and fire networks behave hydraulically as expected, but with more pressure than necessary:
  • Scope to safely reduce pressures by ~20–30 m without compromising service levels.

Recommended Actions

Short‑term operational wins

• Keep the Village 1 bypass permanently closed and blanked.
• Repair / install pressure reducing valves (PRVs):
  • New PRV on Village 1 incoming line, set to around 30 m
  • Repair the failed PRV on the Village 1 MK section
  • PRVs on Village 2 incomers to trim pressures by 20–30 m
• Strengthen controls to prevent domestic use of fire lines.

Targeted maintenance

• Focus leak detection and repair on identified areas.

Results for the Client

For Capital City Housing, the study delivered:

• A definitive picture of where water is actually being lost – and where it is not
• Confidence to avoid unnecessary large‑scale replacements in Village 2
• A quantified leakage and risk profile for Village 1, tied to specific locations and pressures
• A clear, costed roadmap to:
  • Cut non‑revenue water
  • Reduce burst risk on under‑rated mains
  • Protect service to residents
  • Justify future capital spend with solid engineering evidence

The Aloe Ridge work transformed a poorly documented, high‑loss system into a data‑driven asset management plan, enabling CCH to prioritise interventions with confidence.