1) Introduction
Water-retaining structures include potable/non‑potable water tanks, sumps, reservoirs, podium‑integrated pools, and channels. They face sustained hydrostatic pressure, thermal movement near the surface, and frequent penetrations. Systems must be watertight, tile/finish‑compatible where relevant, and maintain bond under head.
2) Exposures and risks
- Continuous hydrostatic head (typically 2–6 m, higher for reservoirs)
- Chemical exposure depending on service (chlorination, mild sulfates/chlorides)
- Thermal cycling at exposed faces and copings
- Movement at corners, junctions, and penetrations
- Negative pressure during emptying for tanks
3) Recommended technologies
Technology | When to use | Key acceptance cues | Read More |
2K Elastomeric Cementitious (internal lining) | Default internal lining for pools, tanks, sumps (tile‑compatible) | Total DFT ≥2.0 mm; 72‑hr fill test pass; corner reinforcement | |
HDPE Pre‑applied bonded sheet | Positive‑side tanking where accessible (rafts/walls before casting) | Seam bond sound; overlaps ≥70–80 mm; no lateral migration | |
PVC Sheet (loose‑laid, welded) | Large basins/reservoirs where double‑weld testing and compartments help | Double‑weld pressure test pass; weld logs recorded | |
Polyurea (spray‑applied) | High‑duty tanks/channels needing rapid turnaround and abrasion resistance | DFT ≥2.0–3.0 mm; adhesion ≥1.5 MPa; chemical spot tests (if applicable) | |
Crystalline (supplementary) | Secondary densification or negative‑side adjunct where rework limited | Two‑coat coverage on SSD; damp‑cure 3 days |
4) Method statement (consultant‑ready)
- Pre‑works and substrate
- Cure concrete to project requirement; grind/clean; repair honeycombs.
- Provide 20×20 mm coves at all internal corners.
- Detailing
- Treat penetrations with primer + bandage system; embed geotextile at corners and around inlets/outlets.
- For positive‑side tanking: ensure substrate readiness, seam QA (sheet systems), and protection layers.
- Membrane/lining application
- Cementitious: 2 coats crosswise to achieve ≥2.0 mm DFT; reinforce corners.
- Sheet systems (HDPE/PVC): overlaps to spec; seam QA (pressure or probe tests).
- Polyurea: primer to key; spray to target DFT in passes; topcoat if exposed.
- Protection and finishes
- Screed/tiles where specified; follow adhesive system class (e.g., C2). Grout with epoxy for durability.
- QA and acceptance
- DFT logs; seam test logs (sheet systems); adhesion pulls where relevant.
- 72‑hr fill test; rectify and re‑test until pass.
5) Add‑ons and decision notes
- Prefer positive‑side waterproofing where accessible; use negative‑side only as supplementary.
- Compartmentalization and re‑injectable hoses are valuable on large tanks.
- For potable applications, confirm product approvals.
Video Masterclass
Conix Masterclass: Water Retaining Structures Waterproofing — Coming Soon
Disclaimer
Conix is an industry initiative & a neutral resource, compiled from industry references and best practices. It is not brand-specific. Always cross-check with project requirements and local codes before finalizing specifications.