I have a cinder block fence and on the outside wall which fall on the street there are stains most likely from water/rain sipping from the yard. I have a desert landscape and just couple bushes, watering is done by the drip system 3 times a week, when the water dripping system start the ground barely gets wet. I have use CLR i bought from home depot that did not work. I used 50/50 bleach water few times which also did not work. I am in HOA sub-division so have got violation notice. I have asked them if they have any suggestion on how to remove this and they have not offered me anything.
Does anyone here have suggestion on how to get rid of the stains. I upload a image file hope it shows up.
Thanks for help and suggestion in advance.

Kstar4u

If you do end up getting rid of the hard water stains... they'll just come back. I'd consider painting the wall with exterior elastomeric (cures kinda' rubbery and expands and contracts with the weather... lots less cracking) Masonry paint.

pan_nv

Yeah but I have to first get rid of the water stains which is proving harder to do.

Kstar4u

You can try using a dilute mixture of water and muratic acid. It actually burns off the outside layer of the cinder block (and anything on it). Use a dilute mixture of muratic acid and water. I would ask the muratic acid supplier for the recommended dilution rate (it might even be on the acid label). Also... the amount of time you leave it on the wall will make a difference. longer means more material removed. Test your solution in an unobtrusive location to make sure you're not gonna' burn the wall down or change the texture of the block. Muratic acid is used to clean and etch concrete but it's really a swimming pool supply. You'll find it in the pool area of Lowes or Home Depot (or at a local pool supply store... it's pretty cheap to buy).

Good Luck