My tank is actively leaking — can I apply CM100 on a wet surface?

For active seeping joints, use FASTFIX WP100 hydraulic cement first to stop the flow. Once water ingress is stopped, allow surface to dry partially and apply CM100.

What is the difference between CM100 and CM200 for water tanks?

CM100 is rigid and specifically designed for water-retaining structures under hydrostatic pressure — tanks, pools, reservoirs. CM200 is flexible for movement-prone wet areas like bathrooms and balconies. For water tanks, always use CM100.

How do I waterproof a swimming pool with Hardex?

Use HARDPROOF CM100 applied in 2–3 coats on cleaned concrete pool shell. Apply SBR-50 primer first. Total coverage 2.0–2.5 kg/m² for pools due to constant water pressure. Allow 28 days before filling.

Water Tank & Swimming Pool Waterproofing

The Problem: Leaking Tanks Waste Water Every Day

Every Drop Lost Is Water Wasted

A 5,000-litre overhead tank losing 10% per day wastes 500 litres. Plus structural damage from constant moisture.

Why Tanks Fail

Construction joints — Junction between base slab and walls is the primary failure point in most tanks.
Honeycombing — Poor concrete placement leaves voids that channel water.
Shrinkage cracks — Concrete cracks as it cures. These are highways for water.
No waterproofing layer — Many tanks are plain concrete with no protection.
Algae and biological growth — Destroys uncoated concrete surfaces over time.

Bitumen paint is the most common fix. It lasts 2–3 years maximum and is not safe for potable water. CM100 lasts 15+ years and is potable water approved.

The Hardex Solution: CM100 Rigid System

CM100 is a rigid cementitious coating — it bonds chemically to concrete and creates a waterproof shell that resists both positive (water pushing in) and negative (water pushing out) hydrostatic pressure.

Hardex Tank Waterproofing System

Step 1 — CRACK REPAIR
FASTFIX WP100 for active leaks · FASTFIX RM40 for structural cracks
Function: Stop active water ingress before coating

↓

Step 2 — SBR-50 SLURRY COAT
SBR-50 mixed with cement · Applied as bonding slurry
Function: Adhesion bridge to substrate

↓

Step 3 — CM100 COAT 1 + COAT 2
Rigid cementitious waterproofing · 0.8–1.0 kg/m² per coat · 24 hrs between coats
Function: Waterproof shell — resists hydrostatic pressure

↓

Step 4 — MOIST CURING + 28 DAYS
Keep damp for 3 days · Full cure 7 days · Potable water safe after 28 days

Feature	Hardex CM100	Bitumen Paint	Epoxy Coating
Potable water safe	✓ After 28 days	✗ Never	Depends on type
Bonds to wet surface	✓ Yes	✗ No	✗ Needs dry
Durability	15+ years	2–3 years	8–12 years
Negative pressure	✓ Yes	✗ Peels off	✗ Debonds

Product Specifications

HARDPROOF CM100 — Rigid Cementitious Waterproofing

1.5–2.0

kg/m² for 2 coats

28

days to potable water safe

15+

year durability

Key property: Resists both positive hydrostatic pressure (water pushing from outside in) and negative hydrostatic pressure (water pushing from inside out). Critical for underground sumps and basement tanks.

FASTFIX WP100 — Hydraulic Cement (for active leaks)

<60

seconds to set

Sets

underwater

Mix &

press — hold 60 sec

First

use before CM100

Use when: Water is actively running from a crack or joint. Plug it first with WP100, then apply CM100 system.

Application Timeline

Day 1

Drain, Clean & Repair

Empty tank. Clean algae, lime scale, loose material. Use WP100 to stop any active seepage. Fill structural cracks with FASTFIX RM40.

⏱ 4–8 hrs depending on size

Day 1–2

SBR-50 Slurry Coat

Mix SBR-50 with cement (1:1.5 ratio). Apply as slurry to damp surface. Apply CM100 first coat while slurry is tacky — do not let dry.

⏱ 1–2 hrs · Proceed while tacky

Day 2

CM100 — First Coat

Apply 0.8–1.0 kg/m² by stiff brush. Work thoroughly into all corners and construction joints. These are highest risk areas.

⏱ 3–5 hrs · Cure: 24 hrs · Keep damp

Day 3

CM100 — Second Coat

Apply second coat perpendicular to first. For swimming pools, apply a third coat at 2.0–2.5 kg/m² total. Keep moist during cure.

⏱ 3–5 hrs · Moist cure 3 days

Day 4–7

Moist Curing

Spray lightly with water 2–3 times daily. Do not allow to dry out — premature drying causes shrinkage cracks in the CM100 itself.

⏱ 10 mins/day · Critical step

Day 8+

Water Fill Test

Fill tank to 25% capacity. Check for seepage at 24 hrs and 48 hrs. If clear, fill to full. Safe for potable water after 28 days from application.

✓ 28 days = potable water safe

Frequently Asked Questions

Is CM100 safe for drinking water tanks?

Yes. CM100 is potable water safe after 28 days full cure. Do not use the tank for drinking water before this. The cementitious coating is inert after cure — no harmful leaching.

My tank has active water running through a crack. What first?

Use FASTFIX WP100 hydraulic cement first. Mix to putty consistency, press into the crack and hold for 60 seconds. It sets even with water flowing through. Only then proceed with CM100.

Can I apply CM100 to a tank that currently has water in it?

No. Tank must be drained and surface must be damp (not wet-running). Drain, clean, repair all active leaks, then allow surface to reach damp condition before applying.

How do I waterproof a swimming pool differently from a water tank?

Same system — CM100 — but apply 3 coats instead of 2 for pools (total 2.0–2.5 kg/m²). Pools face constant water pressure and foot traffic from swimmers. Allow full 28 days before filling.

How long does CM100 last in a water tank?

15+ years with proper application. The cementitious system chemically bonds to concrete — it doesn't peel or delaminate like paint. Lifespan depends on proper preparation and curing, not just the product.

Water Tank & Pool Waterproofing