tap water quality... - Orchid Board

kavanaru · #1 12-12-2007, 09:12 PM

I have a question for the water experts here

According to the yearly report of the water company in my city, our water seems to be very good. They even recommend it for orchids...

pH 7.74 - 7.77
Water hardness 10.8ºdH or 19.3ºfH (not very sure, but I think it is equivalent to 193 in the USA system)

All in mg/L: Fluoride 0.09, Chloride 13.9, Nitrate 9.2, Sulfate 37.1, Bicarbonate 198, Calcium 66.3, Magnesium, 8.5, Potassium 1.8, Sodium 10.3, Silicic acid 5.8

Do you think orchids would be happy or ok with this water?

Pippin · #2 12-12-2007, 10:28 PM

Both Ph and TDS look a bit to high for me.
Do you fertilize with every watering ? If you do, what is your Ph after adding the fertilizer ?
Most hydroponic grade fertilizers will lower your Ph enough to make this water usable, or you can use Ph down solutions to lower it. However if you can it would be a good idea to collect rain water, or if your collection is large enough to install a RO unit.

shakkai · #3 12-13-2007, 12:57 AM

I'm certainly no water expert... but target pH should be below 7. I would also say that the Bicarbonate level is on the high side. I called my water company and was told that TDS was 106, and I still noticed an accumulation of white residue when I used to water with tap water. I now collect and use rain water.

kavanaru · #4 12-13-2007, 02:59 AM

I knew that pH is a bit above the optimal and bicarbonate sounds like too high... however, I was just confused by the declaration of the water company: "our water quality is so high, that even orchids can be watered without especial treatment"

I grow indoor and cannot neither collect rain water nor instal a RO System. I depend on filtered water (Brita filters) which gives a good result. My plants are happy with it, and no residue is seing after all... However, filtering the water for about 70 plants takes quite long. I would be more than happy if I could jump this step

I am changing my plants to S/H in order to facilitate the watering, and which due to the "regular" whole flushing is supposed to help avoiding accumulation of residual minerals and therefore also with constant fertilizing. However, I do not think the fertilizer (in such low dosis) would reduce the pH significantly, especialle due to the amount of bicarbonate in the water...