Most recurring plumbing leaks are not caused by faulty plumbing fittings in Kenya. The problem is often the use of the wrong sealant or adhesive for the specific type of joint.
Residential plumbing systems have three distinct joint types, and each requires a specific chemical solution to create a permanent, leak-proof seal.
Understanding the 3 Main Types of Plumbing Joints
Identifying the type of joint you are working on is the first step in selecting the correct material for a repair. Each joint functions differently under pressure and movement.
Threaded Joints (Taps, Showers)
Threaded joints are mechanical seals found on metallic fittings like taps, shower heads, and gate valves.
These joints rely on the compression of tapered threads to prevent leaks under high water pressure. A thread seal tape (PTFE tape) is not an adhesive; it acts as a lubricant to allow the threads to tighten fully and as a filler to plug microscopic gaps.
Solvent-Weld Joints (PVC Pipes)
Solvent-weld joints are used for connecting PVC pipes and fittings. This process is a chemical fusion, not simple gluing. A purpose-built solvent cement contains aggressive solvents that temporarily melt the surface layers of the PVC plastic.
When the pipe and fitting are pushed together, these molten layers intermingle and chemically fuse into a single, seamless piece of plastic as the solvent evaporates.
Static Compression Joints (Toilets, Sinks)
Static compression joints are non-pressurised seals found at the base of a toilet or around a sink drain.
These joints do not need to withstand high water pressure. Their main function is to prevent seepage and block sewer gases.
These joints require a flexible sealant because fixtures and floors experience minor movements and vibrations that would crack a rigid material like cement.
Mistake #1: Using the Wrong Glue for PVC Pipes
Using a general-purpose adhesive is the most common cause of leaks in PVC pipe systems. These glues cannot create a permanent, waterproof bond that withstands constant water pressure.
Why Super Glue and Rubber Adhesives Fail
Standard super glues (cyanoacrylates) and rubber-based contact adhesives are surface-level glues. They create a brittle, superficial bond that does not fuse the plastic.
Water pressure will eventually force its way through this weak bond, causing the joint to fail. These glues also lack the chemical resistance to handle waste water, degrading over time.
The Correct Method: Using PVC-U Solvent Cement
The only correct method for joining PVC pipes is with a PVC-U solvent cement.
The Dingli PVC-U Adhesive is a purpose-built solvent cement designed for this chemical welding process. Applying the solvent cement to both the pipe and the fitting dissolves the top layer of the plastic.
When joined, they form a continuous, leak-proof weld that has the same strength and pressure rating as the pipe itself. This creates a permanent joint that will not fail under normal operating pressures.
Mistake #2: Sealing a Toilet Base with Cement or Grout
Using a rigid material like cement mortar or tile grout to seal the base of a toilet is a common practice that leads to persistent leaks and foul odours. These materials are unsuitable for this application because they cannot accommodate any movement.
Why Rigid Materials Crack
A toilet and the floor it sits on are subject to minor shifts and vibrations from daily use. Cement and grout are completely rigid and brittle once cured.
This inherent inflexibility means that any micro-movement will cause the seal to crack. These hairline cracks, while often invisible, are large enough to allow water and sewer gas to escape.
The Professional Solution: A Flexible Silicone Seal
The correct material for sealing a toilet base is a 100% waterproof, anti-fungal silicone sealant.
A product like Dingli A6015 Silicone Sealant cures into a tough, flexible rubber that bonds strongly to both the ceramic of the toilet and the floor tiles.
The silicone sealant’s permanent flexibility allows it to absorb vibrations and small movements without breaking the seal, ensuring a long-lasting, hygienic, and completely waterproof joint.
Mistake #3: Improperly Sealing Threaded Fittings
Leaks from threaded fittings, such as taps and shower arms, are typically caused by incorrect application of thread seal tape, not a faulty fitting.
Using Too Little (or Too Much) Thread Seal Tape
The function of PTFE tape is to fill the gaps between threads. Using too little tape (fewer than 3-4 wraps) will leave gaps for water to penetrate under pressure.
Using too much tape can be equally problematic, as it can prevent the threads from engaging properly or even cause the female fitting to crack when tightened.
Relying on Silicone for Pressurised Threads
Silicone sealant is a surface gasket material, not a thread sealant. Applying silicone to the threads of a high-pressure joint is a critical error.
The water pressure will eventually push the silicone out of the threads, resulting in a leak. The only correct material for sealing these pressurized, mechanical joints is PTFE thread seal tape.
Your Basic Plumbing Repair Toolkit
Having a small, dedicated toolkit can handle most common household plumbing repairs. You do not need an extensive collection of specialised tools for these basic tasks.
Essential Tools
A functional kit should include a few core items.
You will need at least two pipe wrenches (one to hold the pipe, one to turn the fitting), a hacksaw with a fine-toothed blade for clean PVC cuts, and a deburring tool or file to smooth the cut edges of the pipe before applying solvent cement.
Essential Materials
The materials are as important as the tools. Your kit must contain the three distinct bonding agents for the different joint types.
This list includes a quality PTFE thread seal tape for threaded fittings, a can of PVC-U Solvent Cement for pipework, and a cartridge of anti-fungal Silicone Sealant for fixtures.
Frequently Asked Questions
Can I join a PVC pipe to a PPR pipe?
You cannot join PVC and PPR pipes directly using solvent cement or heat fusion.
These plastics are chemically incompatible. The only correct way to join them is by using a threaded adapter on each pipe (e.g., a male PVC adapter and a female PPR adapter) and connecting them mechanically.
How long do I wait after gluing a PVC pipe?
You should wait at least 10-15 minutes for the solvent cement to set before handling the joint. Allow at least 2 hours before testing with water at low pressure. For high-pressure applications, you must allow the joint to cure for a full 24 hours to achieve maximum strength.
Is silicone sealant waterproof immediately?
Silicone sealant forms a waterproof skin within about 30-60 minutes, but it is not fully cured. You should not expose the seal to direct water pressure for at least 24 hours to ensure it has cured completely.
Why does my kitchen sink drain leak?
Leaks from a kitchen sink drain are often caused by loose slip-joint nuts or a failed rubber gasket. First, try tightening the nuts by hand. If the leak persists, disassemble the trap, clean all the components, and replace the old gaskets or seals.
