Sprinkler Overspray Is the Single Biggest Cause of Ruined Glass in Idaho

The direct answer: mineral load times heat times repetition

Three things have to line up to ruin glass, and irrigation is the only common source that supplies all three. Mineral load: pressurized canal water delivered by the valley irrigation districts from roughly April 15 to October 15 carries silt and dissolved silica, and municipal or private well water across Ada and Canyon counties commonly tests 7 to 13 grains per gallon, about 120 to 220 parts per million. Heat: a south or west pane in July sits at 130 to 150 degrees Fahrenheit while the air reads 95, so a droplet flashes off in seconds and concentrates its entire mineral content into a ring instead of running down the glass. Repetition: watering three to five mornings a week for six months puts 80 to 150 wet-dry cycles on the same pane in one season, each one stacking on the last. Dust blows off. Pollen rinses off. Mineral bonds, thickens, and eventually etches.

Read the spray pattern before you diagnose the stain

Overspray leaves a signature you can read from the driveway. Damage concentrates in a band from roughly six inches to four feet above grade, is densest on the pane nearest the head, and fades with distance. A fixed-arc head prints its sweep. If a downspout, column, or shrub blocked part of that spray, you get a clean shadow with hard edges, and that silhouette is the proof, because no other source of spotting draws an outline. Check the siding, stone, and screens inside the same band; they will be chalked to the same height. Now rule out the lookalikes. Runoff from a leaching concrete sill or unsealed stone header runs top-down in vertical drips. Construction fallout is scattered evenly across the whole pane. Haze you cannot feel from either side is a failed insulated-glass seal, and no cleaning reaches between the panes. Photograph the band in raking morning light, at an angle, before anyone quotes you.

Three deposits that look alike and need different chemistry

White and chalky is calcium and magnesium carbonate, the ordinary hard-water case, and it dissolves in a mild acid. Orange or rust-brown is iron, common on private wells and on canal water pulled through old steel pipe; standard calcium removers barely touch it, and it takes an oxalic acid product instead. Dull gray-white that shrugs off both is silica, which canal water carries in quantity and which resists mild acids entirely. If your yard runs fertigation, add phosphates and urea to the film. The reason the difference matters is the etching clock. Soda-lime glass is about 73 percent silica held together by sodium and calcium. Water sitting on it swaps hydrogen for sodium, carbonate deposits push the trapped moisture alkaline, and above roughly pH 9 hydroxide dissolves the silica network directly. On a hot, heavily sprayed west wall, the first permanent haze can appear inside one irrigation season. On a shaded north wall it takes years.

Fix the head first, and start with pressure, not aim

Most people re-aim the head and stop there. Aim is the second problem. Spray nozzles are engineered for 30 psi at the nozzle, and valley pressurized irrigation routinely delivers 50 to 80. Past about 45 psi the nozzle stops throwing droplets and starts throwing fog, and fog drifts onto glass 20 to 30 feet from a head that never pointed at the house. A pressure-regulating spray body holds 30 psi and costs eight to twelve dollars on the existing riser, which is the highest-return part on this page. Then geometry. Pull the arc off the house. Swap a 15-foot nozzle for a 5 or an 8 rather than choking the radius with the adjustment screw, because that screw deflects the stream into mist, which is exactly what you are trying to eliminate. Raise short pop-ups above the shrubs bouncing spray upward. Water at 4 or 5 a.m. when air is calm. Convert the foundation bed to inline drip, usually under $200 a zone in parts, and the problem ends permanently.

What a window cleaning will and will not do about this

Here is the part that costs us work. Our standard wash will not fix established sprinkler scale. We clean with 100 percent pure deionized water and no soap, which is the right tool for dirt, pollen, and film and dries to a RainShield finish with nothing left to spot, but pure water gets seconds of contact time on a vertical pane and does not dissolve bonded mineral. Removing that is hard-water restoration: acidic gel, dwell time, fine mechanical work by hand, quoted separately from window cleaning because it is far slower. Two hard cautions. Acid runoff etches natural and cultured stone and dulls anodized aluminum, and in this valley the stone wainscot usually sits directly under the worst pane, so it gets masked and flooded. And razors do not go on tempered glass, because tempering rolls fabricating debris into the surface and a blade drags it into permanent scratches. Check the corner stamp first; patio doors and tall low panels are tempered by code.

The money, including when not to hire anyone

Fresh, light spotting on a reachable ground-floor pane is a genuine DIY job. White vinegar or a hard-water gel, a non-scratch pad, twenty minutes, under ten dollars, and you do not need a company for it. Call one when the deposit is baked in, when the glass is above the first floor, or when you cannot tell whether it is etched. Reflekt window cleaning starts at $199 by pane count, screens are $50, and restoration is quoted apart from the wash. Three things we will tell you on the phone. If a pane is deeply etched, stop buying cleanings for it; a replacement sealed unit runs about $250 to $600 installed and that is the correct spend. If the heads still hit the glass, fix them before restoration, because the result is gone in a season. And the 7-Day Rain Guarantee covers rain, not your own irrigation. Quarterly service saves $100 per cleaning, and its real value here is that no deposit gets older than 90 days.