What Plumbing & Drainage Covers
Plumbing and drainage systems provide potable water supply, hot water, sanitary drainage, stormwater management, and often gas distribution within buildings. Though less visible than HVAC or electrical systems, plumbing failures cause disproportionate damage — water damage is the most common and expensive building insurance claim.
Applicable Standards & Codes
Plumbing Standards in Bangladesh Context
- adopted BNBC 2020 Part 8 (Plumbing) — Basic plumbing and drainage provisions; less detailed than international codes
- adopted WASA Connection Standards — Dhaka WASA requirements for water supply connection and metering
- referenced BS EN 12056 (Gravity Drainage) — Referenced for drainage system design calculations
- silent IPC (International Plumbing Code) — Not formally referenced in Bangladesh regulations or BNBC
| Standard | Scope | Publisher |
|---|---|---|
| UPC (Uniform Plumbing Code) | Plumbing system design and installation | IAPMO |
| IPC (International Plumbing Code) | Plumbing system requirements | ICC |
| WHO Drinking Water Guidelines | Water quality standards | WHO |
| ASHRAE 188 | Legionellosis: risk management for building water systems | ASHRAE |
| BNBC 2020, Part 8 | Plumbing requirements for Bangladesh | HBRI / PWD |
| Bangladesh Safe Water Standards (ECR 1997) | Drinking water quality parameters | DoE Bangladesh |
Key Metrics & Acceptance Criteria
| Parameter | Standard / Source | Good Practice | Red Flag |
|---|---|---|---|
| Water pressure at fixtures | UPC / IPC | 200–500 kPa (30–70 psi) | < 100 kPa (poor flow) or > 600 kPa (damage risk) |
| Hot water temperature | ASHRAE 188 / HSE | 60°C storage, 50°C distribution, ≤ 43°C at TMV outlet | < 50°C storage (Legionella risk) or > 60°C at point of use (scald risk) |
| Water quality — TDS | WHO / Bangladesh ECR | ≤ 500 mg/L (good), ≤ 1,000 mg/L (acceptable) | > 1,000 mg/L |
| Water quality — pH | WHO | 6.5–8.5 | < 6.5 (corrosive) or > 9.0 |
| Tank cleaning frequency | Industry best practice | Every 6 months (underground), annually (overhead) | Never cleaned or no records |
| Water consumption | Industry benchmarks | 50–80 L/person/day (office) | > 120 L/person/day (leak or waste) |
| Drainage system | UPC / IPC | Self-cleansing velocity ≥ 0.6 m/s, proper traps and vents | Odour from drains, slow drainage, surcharging |
What to Inspect on Site
- Water tanks: Condition of underground and overhead tanks — lid sealed? Screened vents? Clean interior? Overflow visible? Algae or sediment?
- Pump room: Booster pumps operational, pressure gauges reading correctly, no leaks, vibration isolation mountings.
- Risers and pipework: Visible corrosion, leaks at joints, pipe insulation condition (hot and cold), support brackets.
- Toilets and washrooms: Fixture condition, flush operation, no running cisterns (water waste), drain odour (indicates dry traps or vent issues).
- Drainage: Check basement sumps, floor drains, grease traps (kitchen/canteen). Evidence of blockages or surcharging?
- Stormwater: Roof drainage connections, gutter condition, downpipes, external drainage gratings — clear or blocked?
Bangladesh Context
- Water supply: WASA (Dhaka Water Supply and Sewerage Authority) provides piped water, but supply is intermittent. Most commercial buildings use underground storage + booster pump systems.
- Groundwater: Many buildings rely on deep tubewells (bore wells). Arsenic contamination is a concern in some areas — test annually. Iron content is common and may require treatment.
- Sewerage: Dhaka's centralised sewerage system covers limited areas. Many buildings use septic tanks or connect to surface drains. Verify the connection type.
- Flooding: Dhaka experiences severe waterlogging during monsoon. Basement and ground floor drainage systems must handle stormwater ingress. Check for flood barriers and sump pumps.
- Water quality: Even piped WASA water requires treatment (filtration + UV/chlorination) before drinking. Point-of-use RO systems are common in offices.
References & Sources
- WHO Guidelines for Drinking-Water Quality
- ASHRAE 188 — Legionellosis Risk Management
- DWASA — Dhaka Water Supply and Sewerage Authority
- UK HSE — Legionella Guidance
- BNBC 2020, Part 8 — Plumbing Provisions (HBRI, Government of Bangladesh)
Insights & Guidance
- Water damage is the most common and expensive building insurance claim.
- Hot water storage at 60°C minimum to prevent Legionella — distribution at 50°C — point of use ≤ 43°C with TMVs.
- Water tank cleaning: every 6 months (underground) and annually (overhead) as minimum.
- Office water consumption benchmark: 50–80 L/person/day. Above 120 suggests leaks.
- Dhaka water supply is intermittent — storage and booster pump systems are essential infrastructure.
- Groundwater arsenic and iron contamination require testing in Bangladesh.
Plumbing failures cause more financial damage than almost any other building system failure. A burst pipe on an upper floor can damage multiple floors below — destroying finishes, equipment, and documents. Legionella from poorly managed water systems can be fatal. In Bangladesh, waterlogging during monsoon can render ground floor and basement spaces unusable for days.
Water quality directly affects occupant health. Contaminated water tanks, corroded pipework, and untreated groundwater are common risks in Bangladesh buildings that require proactive management.
- Pipe burst — corroded or pressurised pipes fail, causing extensive water damage across multiple floors.
- Legionella — bacteria colonises stagnant or warm water (20–45°C). Hot water systems, cooling towers, dead-legs in pipework are all risk areas.
- Contaminated water supply — tank contamination (bird/rodent ingress, algae), cross-connection between potable and non-potable, arsenic in groundwater.
- Drainage blockage — sewage backup into occupied spaces. Grease trap overflow in buildings with food service.
- Monsoon flooding — stormwater overwhelms drainage, enters basement through walls, floor slabs, or backed-up drains.
- Corrosion — galvanised steel pipes corrode from inside; by the time leaks appear externally, the system is extensively degraded.
- Water quality test report — annual laboratory analysis for potable water (pH, TDS, coliform, arsenic, iron, chlorine residual).
- Tank cleaning certificate — date, contractor, method, before/after photos. Every 6 months for underground tanks.
- Legionella risk assessment — for hot water systems and cooling towers. Reviewed annually.
- Plumbing as-built drawings — riser diagram, pipe sizes, valve locations, tank sizes, pump specifications.
- Pump maintenance records — booster pump service history, impeller condition, seal replacement.
- WASA connection documents — approved connection, meter readings, billing.
- Water tank lids — sealed and locked? Vent screens intact? No visible contamination?
- Pipe condition — corrosion on exposed pipework, leaking joints, stains on walls/ceilings below pipes.
- Water colour and pressure at taps — discoloured water indicates corrosion or contamination.
- Drain odour — sewer smell in washrooms or near floor drains indicates dry traps or vent failure.
- Basement condition during or after rain — water marks, pump operation, sump condition.
- Toilet and washroom condition — running cisterns (water waste), cracked fixtures, missing traps.
- What is the water source — WASA supply, borehole, or both? If borehole, has arsenic/iron testing been done?
- What is the water storage capacity (litres)? How many hours of supply does it provide?
- When were the water tanks last cleaned? Is there a scheduled cleaning program?
- Has water quality testing been conducted? What were the results?
- What is the drainage connection — municipal sewer, septic tank, or surface drain?
- Has the building experienced flooding or waterlogging? What measures are in place?
- Is there a Legionella risk assessment for the hot water system?
- Water quality concerns — environmental laboratory testing and water treatment specialist.
- Legionella management — specialist water hygiene consultant.
- Persistent drainage issues — CCTV drain survey by drainage contractor.
- Pipe corrosion assessment — plumbing engineer for remaining useful life evaluation.
- Flood risk management — hydraulic engineer for basement waterproofing and stormwater design.