Rust stains in your pool?

There are basically three causes of rust stains in your pool.  So, before doing anything or wasting any money, make sure you know what type they are and what has caused them to appear.   This page will help you do identify the cause of the rust stains and guide you to the best approach to remove them.  

The three most common types of rust stains in pools are:

  1. Rust from metal objects
  2. Rust from steel used to make the pool
  3. Rust from contaminated pool salt

 (1) Metal objects that have fallen in the pool. 

Most rust stains in your pool come from objects that have fallen into the pool.  This could be a nail, staple, children’s toy, or grinding sparks from cutting metals near the pool.  These types of rust stains will usually leave a stain in the exact shape of the object and be on the floor of the pool.  Quality rust stain removal products can remove these without draining the pool.  The pictures below show examples of rust stain removal without draining the pool or acid-washing the surface.  Don’t worry you can get rid of rust stains in your pool.

Rust Stain in pool
Rust stain caused by a metal hoop on pool step
rust in swimming pool
Rust stains from cutting metal near pool.

You can remove rust stains in your pool.

In many cases, a good quality granular stain treatment will remove rust stains  A good quality stain remover will not damage or discolour the pool surface during the removal process.  It is important to make sure that you remove any loose metal pieces from the pool with the pool vacuum before starting the treatment process. Rememnber, loose metal will continue to rust in the pool and cause the stain to reappear, or not go away in the first place. 

Feel free to contact us if you would like any further information about how to remove rust stains from your swimming pool.  

(2) Rust staining from the steel within the pool structure.   

In these cases, the stain will not look like the shape of an object but appear to ‘weep’ from the pool surface and flow toward the deep end of the pool.  Often these types of rust stains form on the walls of the pool and leave a feint trail of rust running toward the deep end. 

These types of stains occur because the reinforcing steel used in the pool construction has become exposed to moisture and has commenced the process of slowly rusting.  When this happens, the rust stain will usually continually grow and expand over time.  Remember that these types of stains will not respond to any pool stain removal products because the rust will continue to form even if the stain is partially removed.  Also, the repair usually means that you need to drain the pool, cut back the exposed metal, and then seal it with an epoxy resin. Finally, this section of the pool is then re-pebbled (patched) after the repair is complete.  

rust stain in swimming pool
Stain from rusting reinforcing mesh in swimming pool
rust through pool tiles
Rust Stain from rusting reinforcing steel in swimming pool

(3) Rust coloured contaminates from pool salts. 

In some cases, stains can appear soon after adding contaminated or mineral-rich swimming pool salt to the pool.  This type of staining is becoming more common as many pool owners are now switching to mineral-based salts.   We have an entire page about this issue that will give you more information about this type of staining. 

If the rust stain that you have looks like a long brown streak where you normally add the salt or appears very soon after adding salt to the pool, then there is a very good chance that stain contamination is the cause of the stain.  

Salt in swimming pool
Swimming pool surface stained from contaminated salt.

Our top pool repair tips….

Some pool repair jobs can look even worse after the repair has been completed.  The picture below is just one example of what a terrible and very costly repair job can look like after completion. 

We have seen clients drain, acid wash their pool, and replace all the chemicals to remove rust stains only to learn later that it was from reinforcing steel.  When this happens the rust stain usually returns within 3 months.  All of the money, time, and effort to remove the stain is completely wasted.  

Some repairers will suggest that the “colour will change and match over time”.  While there can be some slight colour shifts over time, for the most part, what the pool looks like after it is refilled is basically how it will stay.  It is a good idea to ask the contractor what the next step will be if the colour does not return to normal.  Please note: An exact match is unlikely with pool repairs.  There will be a difference and yes you will notice the patch where the repair has been done.  However, the repair should somewhat blend into the rest of the interior if it is done properly.  

This reinforcing steel repair went horribly wrong.

Our client in Brisbane had a new pool built that was not quite two years old.  Six months after completion, he started to notice some random rust stains appearing on the walls of the pool.  Given that the pool was still new, he contacted the builder on many occasions to see what he would do for him.  After more than 30 phone calls and texts, the builder finally agreed to repair the rust marks in the pool.  

The image shows how his new $100,000 pool now looks after the rust repair.  Our devastated client now has no choice but to go down the road of legal action against the builder.  The builder is claiming that the colour will blend in over time but it is very obvious that this will not happen.  The builder has technically ‘fixed’ the problem but the visual impact of that repair looks significantly worse than the rust did in the first place. 

For these reasons, we suggest that you ask any potential contractor to show pictures of some repairs they have done in the past.  This may give you a guide as to what they see as acceptable quality.  This is good information to have BEFORE you agree to have the work done.  

Pool rust stain repair
This client was heartbroken when his 2 year old pool was repaired. This was the end result.
pool rust stain repair

A Shoddy Pool Rust Stain Repair

This rust repair job cost our client $1,450 in 2022 and now the stains are returning.  Our client was very upset to see the stains return with a vengeance in less than 6 months.  This sad story highlights the importance of getting a reputable and experienced contractor to do any repair work.  

The rust returned because the contractor failed to drill out and seal all of the affected steel.  This meant that instead of being waterproof, the exposed steel was coming in contact with salt water.  This lack of sealing caused the heavy rust stain to come back quite quickly.  She now has to consider either repairing it again or resurfacing the entire pool.  

Rust Stain Remover Treatment

A granular stain compound is used to remove stains from salt or from objects
+/- $300
  • Pool Does not have to be drained
  • Usually removes all rust stains
  • Works on stain caused by fallen objects
  • May need to stay out of pool for 7 days
  • Water can be cloudy for several weeks

Pool Surface Rust Repair (patch)

When steel in pool structure is rusting
+/- $1,500
  • Pool is usually completely drained
  • When done right it is a permanent fix
  • Much cheaper than a new interior
  • Surface colour match will not be perfect
  • New rust stains can appear later as surface ages