Is cast iron used in the plumbing of your house? Do you notice a foul smell and a slow drain? Are you experiencing frequent plumbing problems? Is your water system damaged and the water murky? Rusting of cast iron pipes may be the cause of all your problems.

Cast iron pipes
Cast iron has been used in sewer pipes over the decades. This is because it is extremely strong, heavy, and durable. They can last up to 80-100 years if kept in the right conditions. It rusts and corrodes when it comes in contact with moisture. Rusting cast iron sewer pipes is a major challenge faced. Cast iron is made when the iron is melted, molded, and allowed to solidify. Rusting leads to pipe corrosion caused by hydrogen sulfide gas found in sewages. They collect inside the pipes and are oxidized. The sulfuric acid produced corrodes the walls, making them weak and they eventually crack. The soil beneath the house expands when sewer pipes leak. This causes the foundation of the house to have unwanted motions leading to cracked walls and floors. This depreciates the value of your home.

Signs of rusting
Rust is formed when the iron is irreversibly lost from the cast iron due to its oxidation to iron oxide. Rusting is dependent on:

The moisture content in the air
Degree of protection provided to avoid contact of water with the metal.
Rust build-up suggests internal corrosion in the pipes. It is advisable to completely remove corroded pipes rather than repairing the affected parts to avoid full system failure. Rust reduces the flow of sewer line as:
i. Rust builds up, it constricts the interior diameter of the pipe.
ii. A rough surface is created and this slows down the wastewater flow rate.
 Inspect for rusting by looking for:
Foul smell
Cracked sewer pipes can allow foul-smelling gases to enter your home.
Slow drain
Rust can block pipes causing water to take a long time to drain from sinks, showers, and toilets.
Sewage backups
Frequent plumbing problems
They move through the tiny cracks and into your home.
Brownish or yellowish water
This is an indication of corroded water line pipes.
Blobs on the underside of the pipe 
Wood floors stained with water or loose floor tiles
Moldy walls
Molds will form as long as water leaks from the pipes.
Cracks on walls and floors
This can indicate a big sinkhole has been created under your home. Take this seriously and repair it.
Healthy lawn
Sewage is unhealthy to humans but can be good fertilizer for plants. If you notice patches in the lawn that looks better and green, know there’s a leak.

Maintenance of cast-iron pipes
1) Consider what you pour down the drain.

Avoid using chemical drain cleaners as a way of clearing the clog. The high acidity can deteriorate your old metal pipes. Use a mixture of baking soda and vinegar, plunger, or store-bought enzymes to unclog. If this doesn’t work, call a plumber.
You can clean rust from outside of the pipes if you cannot afford an immediate replacement. Small areas of rust are removed using steel wool and vinegar.
Seal holes and cracks using a plumber’s putty or pipe repair tape.

2) Prevent rust and corrosion.

3) Maintain a good structural condition.

4) Paint and plug holes.

5) Replacing missing pieces with casting materials like epoxy.

6) Checking regularly for water collection spots.

7) Descaling

Cast iron pipes are mostly prone to scaling in the inner surfaces due to magnesium and calcium salts, iron oxide coating. A thick uneven layer of mineral and rust is deposited on the pipe. This picks up solids and sediments that flow past it and it eventually blocks.

         Descaling techniques
Hydro jetting and descaling
A jet of highly pressurized water is blasted into the heavily clogged pipes to remove blockages. A descaling nozzle is then attached to the hydro jet and it blasts pressurized water through the nozzle. The nozzle has a chain that rotates as pressurized water flows, scrubbing the mineral build-up and rust from the surface of the pipe.
Chemical descaling
This is done when the pipe is clear of any other blockages. Chemicals are used to remove scales. An acidic chemical is flushed into the pipes to dissolve rust, magnesium, and calcium salts 
Factors to consider before purchasing pipes
a) Cost
Is it within your budget and has good quality? PVC has been preferred because it is cheaper compared to cast iron.
b) Durability
Iron cast pipes last longer compared to PVC. They are cost-effective as they require less repair. Regular maintenance reduces the risk of rusting.
c) Safety precautions
In case of a fire, PVC pipes will require a total replacement. Cast iron pipes are heat resistant and there will be no need to repair them. When plastic burns, it emits harmful fumes and this can cause health problems.
d) Noise 
PVC pipes highly amplify noise levels compared to cast iron pipes. This is due to the thickness of the pipe in the latter.
e) Aesthetic value
This is dependent on the client’s needs and preferences. PVC may come in different colors and they may attract buyers.
f) Environmental concerns
 Oil-based products are used in the manufacture of PVC pipes. The damaged PVC sewer pipe is not reusable hence trashed. Scrap iron can be used to create cast iron pipes and this is therefore environmentally friendly.

Health effects
Rusted pipes put your health at risk of respiratory diseases. These pipes may leak odorless toxic gases causing you:
Eye irritation
Running nose
Unconsciousness and death in extreme cases

When the sinks, showers, and tubs back up, it is a potential health risk as it can cause infections. Small insects and pests can enter your line using the cracked pipe contaminating your water and causing diseases. Leaks promote mold growth on the pipe and this contaminates the air around your home. A broken pipe can spread pollutants to the underground water supply hence contaminating your neighbor's water supply.

Ways to repair

1. Structural pipelining
A felt liner is soaked in a special epoxy then inserted into the damaged pipe and inflated. It is removed after a few hours and the pipe is lined. This process is quick and cost-effective due to minimal digging. It cannot work on collapsed or back pitched pipes.

2. Pipe bursting
A collapsed pipe lacks structural integrity hence cannot be lined. A brand-new high-density polyethylene (HDPE) pipe is pulled into the damaged pipe breaking and replacing it. It is cost-effective as minimal digging is done to access pipes. 

3. Conventional sewer replacement
This is used when there is intense structural damage to the pipes such that you can’t pull an HDPE pipe through it. It is used to replace collapsed and back pitched pipes. It mostly involves digging.

Cast iron pipes have been used for a long time in history. They are known to be durable and very strong. They have a major drawback and that is rusting. Rusting causes material and structural damage and this is disastrous and needs to be avoided. It is important to do frequent inspections to avoid repairing the entire plumbing system. Hard water, poor maintenance, and age are factors that determine how long a pipe will last. Iron cast pipes are environmentally friendly and preferred. They may have a few health impacts if waste leaks into the water system.