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Rust in old water pipes? Answered

The house I moved in to still has galvanised steel pipes for all water connections.
The rust and deposit build up is so bad that with a pressure nozzle on the garden hose I reach aroun 20m from the tap near the mater meter
but only around 5m in the backyard.
To make things worse these restrictions affect the hot water.
If I open the hot water tap and then open a col water tap the hot slows and then the flow fully stopps.
The landlord already stated he has no intentions of replacing the pipes at this stage as it is quite costly.

The possible solution:
I was thinking of flushing the system with oxalic or phosphoric acid to break down rust and deposits.

The questions:
Has anyone tried this and has some feedback on how good or bad it worked?
Do I have to fill the entire system with the acid or is it enough to get a few liters in and hope it will spread/dilute through the system within 24 hours?
Is it advisable to use a bucket and aquarium pump (probably something stronger) to circulate the acid through the pipes?



Best Answer 10 months ago

The cast iron pipes were pretty common for a while, they used them for sewer lines also. I just replaced the last of mine last year. Besides getting clogged up they also get eaten away over time and start leaking. An argument you can make with the landlord is that replacing the pipes is much cheaper than repairing the water damage caused when a pipe bursts or just gets a hole in it. Some building codes require that the pipes be replaced whenever access to them is available such as when a wall is opened up for any reason.

Because my pipes were a under the floor and not in the walls access to them was not such a problem but laying on my back in the crawl space with all the junk falling on me all the time was not fun.

If there were an easy way to clean the old pipes out they almost for certain will leak when the deposits are removed, and that means they need to be replaced anyway. I will see if I can get some pictures of my old pipes. By the way the old pipes work good for pipe clamps unless they are to fragile and crumbly.

I used PEX for my latest replacements. Supposedly it is superior and can even withstand some freezing without bursting. The line is flexible and so is easier to put in place. You can use a heater or hair dryer to warm it up and make it even more flexible. As a DIY material it not to bad to learn. All the connections are mechanical and there is no glue or soldering involved.

I wonder if the owner would be willing to make a deal with you and provide the materials if you were willing to do the work. You can do it in sections as time allows. I did the hot first and then the cold. Anyway, the landlord would have to be pretty dense not to take an offer like that. Another possibility is to charge for labor but have it taken off in rent rather than cash payments.

So here are some convincing pictures.
The one of the end of the pipe with the threads mostly gone--- This was the main feed line. I went to dismantle it thinking it was going to be tough to get apart. The wrench twisted it off completely. It was only held together by a few threads. It was basically ready to fall apart which would have caused a flood. You can see the deposits inside the pipe also. The water ate the steel away. The other is a 1/2 hot water line that was weeping, always wet. There were 4 places on this pipe that had been eaten through and they were dripping pretty good. The cross section shows the deposits in the pipe. This line had been reduced to a trickle going to the kitchen. I tried back flushing it and got it working a little but the junk that came loose kept clogging the valve in the kitchen sink. This is when I decided to bite the bullet and replace everything. And I narrowly missed a big flood. It may not have made it through another year.

A friend of mine has a cleaning company and does flood repair because he has the equipment to suck up all the water. Insurance companies have contracted with him to do the repairs on some of the houses that have had broken pipes. Its in the tens of thousands for even a small break because they have to tear out everything. It's way cheaper to put in good pipes before it happens.


Some ares I was able to inspect without destroying the pipe look almost as bad as yours.
If you don't mind then I will use your comment and images in an attempt to get my landlord going on a replacement before I try something.

Down here it is not so easy even the landlord would be more agreeing.
For every work you need a tradesman doing it.
Otherwise you won't get money back from the taxman and if the insurance finds out you loose that too.
Part of a clamp down on "illegal" DIY building and renovation works made by landlords.
Dealing through real estate agents for this is not making it easier so I now tried several emails asking for an appointment in the house with the landlord itself.
Nothing beats personal contact and for an owner to actually see what everyone is talking about.

It is part of the culture here, at least for those owning houses to rent out.
Try to get half decent tennants any only invest if there is no way out.
Up to the point where you pay the same rent for new and 50 year old houses that never saw any renovations.

I can only think of a catalyzer or catalyst for breaking down the stuff, but that would be pretty expensive and very slow. Is that what it's called in English?

As others have said, I wouldn't disturb the insides of the pipe as that rust may be holding back some water from leaking. Also, I don't know what prices are like down under, but I believe PEX pipes would be cheaper per foot as well as installation time. Other than that, I don't have much to add as Vyger answer is pretty damn good.

Problem is that any kind of replacement is only good if done complete.
Here it means replacing and getting access to 7 hot water outlets and 9 cold water ones.
Some taps are in tiled walls, others within walls covered by fixed cabinets mounted to floors/walls.
The material coasts are not really the issue for my landlord, the labour costs and what is involved to replace the pipes from meter to all taps is turning him off.
So far the lowest quote was $3800 AU not including the works on cabintes, walls and tiled area.
The highest including replacing all taps/mixers and damages to walls, tiles and so on is just under 9 grand...
So if the pipes would be replaced it would only make sense with further renovations/upgrades/replacements, driving the costs even higher.
After all you can't just ruin walls and cabinets and if for example the kitchen is over 30 years old....
Biggest problem seems to be the limited crawl space under the house and the fact that all pipes in the walls go through holes in the floorboards.
Seems they did the floors and framing, then the plumbing before putting walls on.

In the Uk you can buy inhibitor. This goes into the heating system circuit which has steel radiators in it to prevent them rusting.

We also have a magnetic filter to remove any rust that does get into the system.

Our drinking and washing system is all copper or these days plastic pipe.

I think flushing your pipes has a danger of revealing leaks. CokeaCola contains phosphoric acid - perhaps you could use that. :-)


10 months ago

30 years ago we had 3/4" iron pipes to our home that were almost fully clogged like yours, our second floor shower was a single stream..

A friendly handyman dug a ditch and laid 1" drink PVC pipe from the home to the 3/4" water-shut-off at the main water line running along our street.. The iron pipe was abandoned.. The second floor shower is running strong to this day..

I offer this as a possible solution in place of your chemical assault, which may even cause a leak to develop under ground..

Best of luck with pipe situation..