Well Waterproofing

Wells have been serving humanity for thousands of years, built for a variety of purposes. While their design has evolved over the centuries, they remain an essential tool in daily life.

A well is a man-made, drilled, or excavated hole that reaches the water-bearing level. It is typically constructed using reinforced concrete rings stacked on top of each other. These rings are often installed using standard cement mortar, without proper waterproofing.

However, fluctuating temperatures and, most importantly, the harmful effects of salts in water can damage the connections between rings. This deterioration can result in:

• Water contamination from sand, clay particles, and soil.
• Potential infiltration of harmful chemicals from the surrounding ground.
• Cracking in the concrete rings, leading to structural weakening.

It’s important to note that replacing damaged rings is far more expensive and labor-intensive than applying proper waterproofing during the initial construction phase. A well-sealed well will remain protected for many years.

The well after pumping out the water

Case Study: Well Waterproofing

Problem: Leaking joints between well rings, Leaking pipe connections, Water seeping through the bottom slab at the base of the well.

How to Waterproof a Well?

1. Sealing Pipe Penetrations

The first step in sealing pipe penetrations is chipping out the area around the pipe to create enough space for applying the sealant with a 1 cm diameter nozzle applicator.

Next, apply KOESTER KB Flex 200 around the pipe to form a tight seal, ensuring a minimum thickness of 8 cm within the wall.

Leave at least 2 cm from the wall surface to allow for sealing the application.

Use KOESTER WASSER STOP or KB FIX 5 (fast-setting waterproof mortar) to secure the seal.

Additional Sealing Layer

A sealing slurry should be applied around the sealed area, using one of the following products:

• Bostik K11 Schlämme Grau
• KOESTER NB 1
• KOESTER NB Elastik
• Schomburg Aquafin 2K/MPplus (PZH-certified for drinking water safety)

The slurry should be applied 10-15 cm around the pipe penetration and extended at least 10 cm onto the pipe itself.

Preparation for PVC Pipes

1. Clean the surface of the pipe.
2. Apply Bostik A936, a primer for non-absorbent surfaces.
3. Apply the first layer of waterproofing using Bostik K11 Schlämme Grau, KOESTER NB 1, KOESTER NB Elastik, or Schomburg Aquafin 2K/MPplus.
4. Embed Bostik Sanitary Band at the wall-to-pipe connection to reinforce the seal.

Sealing the Joints Between Well Rings

The joint should be chiseled into a dovetail shape. This method ensures that the sealing mortar is locked in place, preventing it from being pushed out of the joint. Simply widening the joint without this shaping would not provide a secure seal.

Use one of the following sealing mortars:

• Bostik Rapid 3
• Bostik Rapid 8
• KOESTER Wasserstop
• KB FIX 5

After sealing the chiseled joint, a waterproofing band should be applied over the sealed area using a PZH-certified sealing slurry.

Applying the Waterproofing Band

1. Clean the well rings using a wire brush, covering 15 cm above and 15 cm below the joint.
2. Remove dust and moisten the surface before applying the first layer of slurry.
3. Apply one of the following waterproofing slurries:
   • Bostik K11 Schlämme Grau
   • KOESTER NB 1
   • KOESTER NB Elastik
   • Schomburg Aquafin 2K/MPplus

Properly executed sealing significantly extends the lifespan of a well. For long-term durability, high-quality materials and professional application should not be overlooked.