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Home » Renovation » Best Drain Cleaner for Cast Iron Pipe (FULL Guide)

Best Drain Cleaner for Cast Iron Pipe (FULL Guide)

Best Drain Cleaners for Cast Iron Pipe

The best drain cleaner for cast iron pipe clears blockage caused by any clogging matter. Here’s our full guide to the most suitable options.

You don’t always require the services of a plumber. You can clean the pipes yourself and the drain cleaners do not harm the pipes too.

Homeowners hate the mess, smell, and expense of dirty and clogged cast iron pipes. That’s why they use a reliable drain cleaner designed for cast iron pipes to avoid and correct the issue.

There are various drain cleaners for cast iron pipes on the market. You can buy one in an improvement store or home center near you. Others are available via online retailers. Picking the effective one is tricky, but it doesn’t have to be so with the following top reviews.

Considering some factors before buying, as described in this guide, makes it a breeze to choose the right drain cleaner for cast iron pipes.

Best Drain Cleaners for Cast Iron Pipes

Top Drain Cleaners for Cast Iron Pipes

Best Drain Cleaners for Cast Iron Pipe

1. Zep Drain Cleaner powder Safe for Cast Iron Pipes and Septic Systems


  • Enzyme-based formula
  • Come in liquid or powder form
  • Weighs 1.12 pounds
  • Made by Zep
  • Package dimensions of 7.6 by 7.32 by 3.78 – inches

Zep Drain Defense Enzymatic Drain Cleaner for cast iron pipes is designed to remove build-up accumulated over many years. It consists of an enzyme formula that breakdown hair, grease, food particles, and anything else clogging your cast iron pipe.

It’s easy to use. Plus, it comes in liquid or powder form, too. Both types perform the same. You only need to pour 1 ounce of the liquid formula into your drain. Then follow with 16 ounces of warm water.

You will need to premix the powder drain defense before use. Add 1 ounce of the powder into 16 ounces of warm water. Then pour the mixture into your drain.

The ingredients are safe for cast iron, PVC, and other septic systems. They mix with the clogging items and break them down into water, carbon dioxide, and minerals. 

Bad smells dissolve too from pipes and septic tanks, allowing you to enjoy the fresh air.

Having been certified and made by a renowned brand, you can buy Zep Drain Defense Enzymatic Drain Cleaner confidently. Besides, it will last 40 treatments, keeping your pipes clean and clog-free for an extended period.

Still, using the drain cleaner for cast iron pipes once a month protects your pipes against future clogs!


  • Dissolves all clogging items fast and protects against future clogging
  • Easy to use
  • Removes odor
  • Lasts for a long period
  • Safe to use


  • Requires multiple applications for heavily clogged pipes
  • It removes grease slowly

2. Liquid-Plumr Pro-Strength Cast Iron Pipes Clog Remover & Full Clog Destroyer


  • Liquid form
  • Weighs 32 ounces
  • Made by Liquid-Plumr
  • Triple-action formula
  • PipeGuard technology

Are your cast iron pipes fully blocked? Liquid-Plumr Pro-strength Clog Remover got designed for you. Its triple-action formula will work like magic to remove any stubborn blockage without damaging the pipes.

The drain cleaner for cast iron pipe coats the entire pipe, dissolving any clogging matter like food, soap scum, or hair. After using it, grime does not stick to the pipe walls because the drain cleaner leaves a repellent barrier.

Still, you can continue using it at least once monthly to keep the pipes clog-free.

Despite unclogging fully blocked pipes effectively, many users get wowed by its ability to fight odors. It’s also a cinch to use it. Just pour 16 ounces into the drain. Then wait for 15 minutes and pour hot water. Your pipes will then restore to a clear flow!

Safe drain cleaner for cast iron pipe works best in garbage disposals and slow-flowing sinks. You can also use it on new or old pipes of any materials, such as copper, plastic, and PVC.

Most users prefer using it in their stinky sinks and fully clogged drains.


  • Clears fully clogged pipes, slow flowing drains, and garbage disposals
  • Refreshes stinky sinks
  • Easy to use
  • It protects pipes and is safe to use in all septic systems
  • It prevents the formation of grime


  • It leaves hands feeling slippery if in direct contact
  • Some users think it’s overpriced

3. Instant Power Drain Cleaner Liquid & Clog Remover for Septic System


  • Super-charged formula
  • Weighs 4.7 pounds
  • Green liquid
  • Unclogs and treats septic tanks
  • Liquefies organic materials

Instant Power Septic Shock Septic Tank treatment is formulated for users having trouble with their septic tanks and drains, and requires an instant solution.

With an effective super-charged formula, it leaves your drain clear and de-clogs your septic tank within minutes. It’s the best drain cleaner for cast iron pipe to use in an emergency.

Capable of treating a septic tank with a capacity of up to 1,500 gallons, the drain cleaner is truly powerful and effective. No wonder it’s famous with most homeowners.

The enzymes in its formulation break down anything clogging the pipes and open lateral lines. In return, it prevents septic backups. The drain cleaner for cast iron pipe does not damage the pipes either.

In addition to clearing your pipes and septic tank, it eliminates the bad smell. Unlike most drain cleaners on the market, the Instant Power Septic Shock Septic Tank treatment contains no harsh acids and chemicals.

It’s also a doddle to use. You only need to pour two liters of the safe drain cleaner for cast iron pipe into your toilet and flush.

You can use it to clean, freshen, and unclog your home or RV.


  • Acts fast in unclogging pipes and treating septic tanks
  • It contains no harmful chemicals
  • Easy to use
  • Ideal to use in homes and recreational vehicles
  • Breaks down all blocking matter


  • Irritates when inhaled
  • Not ideal for allergic people

4. Zep 10 Minute Drain Opener Commercial Strength, Fast Acting, and Safe For All Pipes


  • Gel Form
  • Weighs 38.14 pounds
  • Comes in four packs
  • Fast acting
  • Safe on pipes

Is hair clogging your cast iron pipes? Zep 10 Minute Drain Opener Gel 1 Gallon could be your quick solution. The liquid drain cleaner for cast iron pipe got designed to dissolve hair within 10 minutes!

It also breaks down all grease in drains, allowing a smooth flow. That’s why the enzymes for cast iron pipe work best in shower drains, bathroom tubs, and sinks. You will need another drain cleaner like Zep advance kitchen sink drain opener gel to unclog your kitchen sink.

Unlike some drain cleaners, the formulation does not cause rust or damage to your cast iron pipes. It doesn’t affect other pipes of different materials, such as plastic and brass. Instead, it protects them and ensures water runs smoothly.

Using it is a breeze. Pour 16 oz. of Zep 10 Minute Drain Opener and wait for the clog to clear. Then rinse using hot water. It only works on standing water, making it unsuitable for flushing it via your toilet.

Also, having been made by Zep, a reputable drain cleaner maker, you are guaranteed quality and performance. It’s also a great deal for your money.


  • Dissolves hair and grease in 10 minutes
  • Does not harm the plumbing system and septic tanks
  • Works excellently on shower drains, and bathroom tubs and sinks
  • Easy to use
  • Affordable


  • You cannot use it in the kitchen sink
  • Not ideal to use on the toilet

5. Green Gobbler ENZYMES for Controlling Foul Odors & Breaks in Septic Tanks


  • It comes as a set of four gallons
  • Powerful digestive enzymes
  • Dissolves grime and grease
  • Weighs 36.3 pounds
  • Chemical-free

If you are searching for an all-purpose, safe-to-use drain cleaner for cast iron pipe, you may need to consider Green Gobbler ENZYMES. It’s designed to clear drains, sinks, disposals, RV & Boat holding tanks, grease traps, septic tanks, sewers, wet wells, and other collection systems.

Its degradation technology makes it one of the top drain cleaners for cast iron pipe to use in all your clogged systems. The enzymes effectively break down fats, proteins, greases, cellulose, oils, and other food matter blocking the pipes.

What pleases users more about the product is its safety. Green Gobbler ENZYMES is a safer alternative than drain cleaners containing sodium hydroxide or other harmful chemicals.

It’s an involving task to pump out a septic tank. Plus, it was expensive, too. Also, using Green Gobbler ENZYMES reduces the frequency of pumping out your septic tank, saving you time and money.

The enzymes for4 cast iron pipe also act fast in eliminating odor, refreshing the air almost instantly. It’s also easy to use in your new or old plumbing system.


  • Unclogs all plumbing systems
  • Removes grease traps
  • Eliminates smell
  • Easy to use
  • Safe to use


  • You can only use one gallon at a time
  • It does not eliminate drain flies

6. Rid-X 3.2 oz Septic Tank Treatment Enzymes and Drain Cleaner for Cast Iron Pipe


  • Three dissolvable tabs
  • Weighs 0.2 pounds
  • Safe for all pipes and septic tanks
  • Scientifically proven to break down waste
  • Designed to prevent septic backups

Are you searching for a drain cleaner to unblock your old cast iron pipes and prevent your septic tank from backing up? Rid-X Septic Tank Treatment Enzymes do more than that. It will also treat your septic tank by working on the waste, preventing a septic backup.

Its 5-in-1-waste-digestion formula makes it one of the market’s best drain cleaners for old cast iron pipes. Septic professionals use and recommend it. The enzymes completely dissolve proteins, papers, oils, starch, and grease, blocking your plumbing system.

It comes in three easy-to-dissolve tablets, and you can only use one monthly. You only need to put one tablet in the toilet and flush it. The enzymes for cast iron pipe will go dissolving any blocking matter down the drain to the septic tank.

Since it’s a set of three tablets, you can only use it for three months. Some users make it a habit to flush one tablet each month to maintain the system clean and prevent it from clogging.


  • Prevents sewage backup
  • Easy to use
  • Digests septic sludge effectively
  • Unclogs pipes fast
  • Affordable


  • You can only use it three times
  • It will irritate the eyes if in contact and is not suitable for persons with allergies and respiratory disorders.

7. Roebic 32 Ounces Cast Iron Septic System Cleaner


  • Septic system cleaner
  • Emergency care
  • 32 ounces
  • Packed in a plastic container
  • Formulated using powerful bacteria

Are you experiencing a septic backup or pipe clogging that requires emergency attention? Roebic K-57-Q Septic System Cleaner got designed for such situations. Its effective formulation containing powerful bacteria reopens an entire piping system.

It’s a safe drain cleaner for cast iron pipe too. The formulation does not contain any corrosive material, meaning it does not affect any pipe type. Plus, it’s friendly to the environment, too.

Having developed by Roebic, a company that has been developing quality products for over the last 50 years, you get guaranteed nothing less than quality and high functionality. Besides, it’s certified biodegradable.

Using is a cinch. You only need to pour it into your septic tank or cesspool. Alternatively, you can pour it into the toilet and flush it.

Each plastic jerrican contains 947ml of Roebic K-57-Q Septic System Cleaner and is enough to treat a 500-gallon system. The formulation digests paper and other clogging matter, clearing the pipes immediately and preventing a septic backup.   


  • Acts fast in emergencies
  • Safe to use and environmental-friendly
  • Economical
  • Highly-functional and certified
  • Easy to use


  • Harmful if taken internally
  • It May be pricey for some users

8. Zep Commercial ZLDC648 64 0z Iron Pipe Drain Cleaner


  • Green gel
  • Weighs 4.75 pounds
  • Powerful enzyme formula
  • Designed to unclog slow drains
  • Features a lovely scent

Zep Commercial ZLDC648 64 Oz Drain Care got formulated to open slow drains. Having been made by Zep Commercial, a successful giant in the industry, its performance is a guarantee.

The formulation contains enzymes that degrade any matter that has build-up over the years, causing a slow or fully blocked drain. In return, the plumbing system becomes clear, and water flows seamlessly.

If you want to take care of your drain, the liquid drain cleaner for cast iron pipe is among the top options. When used once per month, you get guaranteed a clog-free piping system.

Some drain cleaners damage pipes and septic systems, but not the Zep Commercial ZLDC648 64 Oz Drain Care. Instead, it keeps the pipes clean, clear and freshened while it prevents septic backup.


  • Unblocks slow drains
  • Prevents drain blocking
  • Keeps the pipes and septic tanks safe
  • Dissolves build-up accumulated for many years
  • Pocket-friendly


  • Not the best to remove outside clogs like roots
  • Used only once or a few times, depending on the nature of the clog

9. RID-X 48 oz Septic Treatment and Cast Iron Pipes Cleaner


  • Liquid form
  • 48 oz
  • 6 monthly doses
  • Scientifically proven to breakdown waste
  • Treats septic tanks

RID-X Septic Treatment got formulated with 100% natural bacteria and enzymes to prevent sewage backup. Sewage solid can easily build up without getting noticed, causing a septic backup. Putting this enzyme for cast iron pipe into your piping system unclogs the pipes and breaks down grease, toilet paper, and other wastes that can affect the septic system.

It comes in a 48 oz. jerrican that last six months. You only add it once per month into your septic tank to balance its content and keep it functioning well.

The drain cleaner for old cast iron pipes has existed for over 50 years and has won the hearts of millions of users with its excellent performance. Even septic experts use and recommend it.

The best way to put it in your plumbing system is by flushing it down your toilet. You don’t have to wait or mix anything, preventing you from making any mess.

The manufacturer formulates this drain cleaner for cast iron pipe in three forms; liquid, powder, and septic pacs. You can buy the form you want as they all perform equally.


  • Balances septic content to prevent a backup
  • Unclogs all types of pipes without damaging them
  • Easy to use
  • It comes in three different forms to serve various preferences
  • Trusted by experts


  • Prolonged contact may cause mild skin irritation
  • Irritates the mucous membranes and lungs when inhaled

10. Patriot Chemicals 1 Gallon 100% Active Natural Citrus Degreaser Cleaner & Deodorizer 100%


  • It comes in one gallon
  • It contains 100% active natural citrus degreaser
  • D-limonene industrial strength
  • Deodorizes
  • Environmentally save

Formulated with 100% natural ingredients, Patriot Chemicals Sales 1 Gallon Drain Opener is one of the safest cleaners to clean and unclog your pipes. It does not harm all pipe types and is 100% environmentally safe.

Users prefer the drain cleaner for old cast iron pipes for its multipurpose feature. It’s perfect for sewer plant cleaning. The formulation breakdown sewage matter, preventing a backup.

Also, the natural citrus degrease unblocks pipes by removing grease that accumulates and blocks pipes. You only need to pour it into your sink or tub drains. Then follow with hot water after 10 minutes. It clears all the tub and shower soap scum, too.

It’s also a great product for pet owners. It removes odors left behind by pets on surfaces, floors, and other places. The drain cleaner for cast iron pipe is an excellent stain remover on natural fiber clothing. You only need to apply it to the greased or soiled area. Then wash using a detergent.

Patriot Chemicals Sales 1 Gallon Drain Opener also removes tire marks, tar, asphalt, bumper sticker, and decal. Mixing some with water leaves your dumpster and garbage truck clean, too. Some users use it to remove stains on concrete.

Though it may be pricey, every dime is worth it!


  • Multipurpose drain cleaner
  • Ideal for industrial sewage plant cleaning
  • Ideal to use on all metal surfaces
  • Kills bad smell
  • EPA-approved, green, and biodegradable


  • It might be expensive for some users
  • All sales are final, and the company is not reliable for any injury or damage caused by misuse

Buying Guide of the Best Drain Cleaner for Cast Iron Pipes

Though the above drain cleaners for cast iron pipes are great, not all will meet your specific needs and budget. You should consider some factors before buying to get the right one. Those factors include the following;


Various things cause clogging in pipes. Before buying a drain cleaner for cast iron pipe, determine the clog type you’re dealing with. If your kitchen plumbing system has an issue, it’s likely that food matter and grease could be causing the blockage.

Bathroom piping system clogging could result from hair and soap scum build-up, among others. Some drain cleaners get designed to break down certain clogging matter. Consider buying a drain cleaner designed for the clogging matter you’re dealing with.

Alternatively, you can opt to buy one that removes all types of clogging matter.


It is wise and economical to go for a drain cleaner that will unblock your clogged iron pipes and perform another task. For example, if you are experiencing a blockage in your pipes and your septic tank is backing up, you can buy a drain cleaner that unblocks and prevents septic backup.

It would be expensive and tasking to buy a drain cleaner and a septic tank treatment separately. Considering one that sorts all the problems will save you time and money.


Consider if the situation requires immediate attention when buying a drain cleaner for cast iron pipe. The market has drain cleaners that act instantly, while others are effective after a few minutes and hours. If your pipes are not delivering waste, it’s advisable to use a drain cleaner that works immediately.

You can sort slow drain with a cleaner that works after a few hours. Some work best when left to sit overnight.


Not all drain cleaners are perfect for cast iron pipes. Before paying for one, investigate whether it’s suitable for cast iron pipes. Ensure it contains no ingredients that can harm or damage your cast iron piping system.


What gets used in making a drain cleaner for cast iron pipe matters because it determines whether the product is effective and safe. Some drain cleaners contain an awful smell and can irritate your respiratory system. Others are not environmental-friendly.

A good drain cleaner is certified and safe for the user, piping system, and environment. It also unblocks your pipes effectively and removes the bad small.


It’s essential to consider the amount of drain cleaner used for each unblocking task. You will need to use the entire dose per unclogging for some. For others, the quantity can be used once per month, several times.

A drain cleaner usable several times is more economical and time-saving than a one-time use product.


Drain cleaners for cast iron pipes come at different prices. The quantity and ingredients used in making them determine the price. Some cost more but come in large quantities to serve you for an extended period. Others may be cheaper but small in quantity.

Some drain cleaners for cast iron pipes may come packed in small quantities but are very expensive. It could be the formulation is very effective, and you only need to use a small amount for your unclogging task.

Whichever you go for, ensure it sorts your needs and fits your budget.

After buying a drain cleaner for cast iron pipe, how do you use it? Here is the insight;

How to Clean Out Cast Iron Drain Pipes with Drain Cleaner

Cleaning Out Cast Iron Drain Pipes with Drain Cleaner

Step 1: Buy a Safe and Effective Drain Cleaner

It’s the first thing to do. You cannot start the process without the right drain cleaner.

Before buying, determine the cast iron plumbing system you want to clean. Is it for your kitchen, toilet, or sewer? Then buy the appropriate drain cleaner that will remove specific clogging materials.

Step 2: Put the Cleaner into the Drain

Each drain cleaner has its way of using it. You should read the manufacturer’s instructions before use.

You’ll need to flush some down the toilet while others get poured into the drain. Whichever way, ensure you follow the manufacturer’s instructions.

Step 3: Follow the Manufacturer’s Guide

Depending on the drain cleaner you use, you may need to do more after putting it into the drain. According to some manufacturers’ instructions, you may need to allow the cleaner to sit for some time. For example, after some hours or overnight.

Others require you to pour a certain amount of hot water after pouring it inside the drain. Pouring the cleaner into the drain is all that’s required for some. Whichever the case, do it.

Step 4: Test the Drain

After putting the clear into the drain and allowing it enough time to do the work, test if the pipes are clean. Run water through the pipes to check if it’s flowing as required.

If running down the pipes slowly, it means that the pipes are still clogged or dirty. Add some drain cleaner and give it time to break down all the clogging matter.

When the water flows at the required speed, you’ll have successfully cleaned your cast iron pipes with a drain cleaner.

Though this guide gives much information about drain cleaners for cast iron, you may still have some questions you want to get answered. To help you out, here are answers to some of the frequently asked questions.


1. Is Drain Cleaner Safe for Cast Iron Pipes?

It depends on the drain cleaner you want to use. Some are made with safe ingredients, like enzymes, and don’t harm cast iron or other pipe types.

Others contain harmful chemicals that damage or cause corrosion to the cast iron pipes. You should check the cleaner’s composition before use.

2. Does Drano Damage Cast Iron Pipes?

Does Drano Damage Cast Iron Pipes

No. Drano contains a strong formulation that unclogs even stubborn blockages. But it does not damage the pipes despite their material. The formulation contains an ingredient that prevents the pipes from rusting.

3. Will Vinegar Hurt Cast Iron Pipes?

Will Vinegar Hurt Cast Iron Pipes

Vinegar and water mixture prevents rusting in iron cast products and pipes. It’s also one of the mixtures that clean the pipes effectively without causing them any harm.

If you have no budget for a commercial drain cleaner, try a vinegar mixture as a home-based remedy.

4. Is CLR Safe for Cast Iron Pipes?

Is CLR Safe for Cast Iron Pipes

CLR contains acids that react with cast iron pipes, causing them harm. It may clear sluggish drains and household clogs in minutes, but it will compromise your cast iron pipes.

If in contact with cast iron pipes, rinse them immediately with cool water.

5. Is Bleach Safe for Cast Iron Pipes?

Is Bleach Safe for Cast Iron Pipes

No. When in contact with cast iron pipes, a reaction occurs, resulting in corrosion. Also, bleach does not break down certain clogged matter, such as hair, food bits, and grease.

Plus, it can react with other chemicals to create dangerous fumes or a violent reaction that can bust the pipes.

6. Is Sulphuric Acid Safe for Cast Iron Pipes?

Is Sulphuric Acid Safe for Cast Iron Pipes

No. It causes corrosion on cast iron. Sulphuric acid accumulates on cast iron pipes with time. If not removed on time, they cause the pipes to break or crack.

If you see your pipes draining slowly, sulphuric acid may have accumulated on their walls.

7. Is Hydro Jetting Safe for Cast Iron Pipes?

Is Hydro Jetting Safe for Cast Iron Pipes

Yes. Hydro jetting is safe for all pipe types regardless of their age. But you must not use it on damaged or fragile pipes as it may worsen the situation.

Hydro jetting entails highly pressurized water that effectively removes stubborn debris and other clogging matter. It’s performed once every 18 – 22 months.

8. How Long Does a Cast Iron Drain Pipe Last?

A cast iron pipe can exist for 50 to 100 years with proper maintenance. But if you notice deterioration before then, it’s advisable to replace it.

Final Thoughts

All the drain cleaners for cast iron pipes reviewed above are great, but Zep Drain Defense Enzymatic Drain Cleaner Powder ranks top. It clears clogs in showers, toilets, and sinks effectively.

It’s an enzyme-based formula that breaks down all types of clogging matter. Plus, it clears build-ups that have accumulated for a long period within a short time. Still, when used every month, it protects the pipes from blocking.

You can use it confidently as it works optimally and does not harm all pipe types. It’s also safe when in contact with your hands.

But if you have other needs, such as treating your septic tank and preventing a backup, you can choose a drain cleaner specifically formulated for that purpose. Use the above best drain cleaner for cast iron pipe list as your starting point.