After drainage pipes + manholes are installed, you cannot see inside them — leaks, cracks, missed joints are invisible. A Smoke Test is the cheap, fast, definitive way to find them: pump theatrical smoke (non-toxic) into the drainage system at one end; observe escape points at the other; any visible smoke escape = leak.

Smoke tests are particularly powerful for storm-water + low-pressure sewer systems where hydrostatic testing isn't practical (gravity systems, with bypass connections, with multiple outlets). The test takes 30-60 minutes per system; equipment is portable; results are visible.

For major infrastructure projects (urban drainage, sewerage networks), smoke testing is often mandatory pre-handover to verify the as-built integrity of the system.

Equipment: - Smoke generator (electric / chemical-cartridge powered) - Blower / fan to push smoke through pipes - Theatrical-grade non-toxic smoke (white / titanium dioxide based) - Plugs to seal alternate openings (so smoke goes where intended) - Camera + recording device

Procedure: 1. Pre-test inspection — verify all pipes laid + backfilled to pipe-crown level; manholes complete with covers; no obvious damage 2. Plug alternate routes — close off branches not under test; main path open 3. Setup at upstream point — connect smoke generator + blower to upstream manhole / cleanout 4. Generate smoke — typically 5-10 minutes for medium-sized network 5. Walk the alignment — observe ground surface for escaping smoke (indicates broken pipe / leaky joint); observe at downstream openings for normal flow 6. Photograph all escape points with GPS coordinates / chainage references 7. Stop smoke — let system clear (5-10 min) 8. Mark + repair all leak points; re-test the repaired section

Acceptance: typically zero smoke escape from buried sections; acceptable minor escape at exposed inspection chambers / manholes (where cover seal may be imperfect).

1. Cracked pipes — smoke escapes through fracture lines; pinpoints damaged sections

2. Failed joints — rubber-ring failure, solvent-cement joint not bonded, concrete joint cracking; visible smoke escape at joint area

3. Illegal connections — homeowner / shop has tapped into the storm drain illegally; smoke escapes at that connection; the connection is identified for legal action / proper integration

4. Cross-connections — storm + sewer cross-connected; smoke from one shows up in the other → cross-flow during heavy rain causing flooding

5. Damaged manhole walls — smoke escapes through cracks in chamber walls / cover bedding

6. Lost connections — branch pipe to street drain has been damaged or not connected; smoke escapes at ground level

7. Inadequate ventilation — sewer gas accumulation indicates blocked vents; smoke test reveals where vents are needed

The test is inexpensive (₹3,000-10,000 per section) but extremely high-value — finds millions of rupees of latent defects.

Companion QA/QC: - Sewer Method Statement (QC-DRN-FRM-001) — construction methodology - Manhole Method Statement (QC-DRN-FRM-002) — manhole construction - Drainage Register (QC-DRN-REG-001) — system-level tracking - Hydrostatic leak test — companion for pressurized pipes

Codes: - IS 4127:2017 — Code of Practice for Laying and Construction of Sewers (test methodology) - IS 458:2003 — Precast concrete pipes - CPHEEO Manual on Sewerage 2013 — National sewerage manual (includes commissioning + acceptance testing) - NACHI standards — international standards for smoke testing methodology