First, when you measure pH, you should measure what comes out of the pot after it has gone through the medium, what comes from the tap is just the beginning of the story.
An interesting "aside" ... Fred Clarke reported that Orchiata becomes more acidic with time, that they do calcine the bark to make it pH neutral and that washes out. (An argument for NOT soaking it) Apparently the Kiwi bark that he prefers doesn't have that issue. BUT... he uses RO water throughout the nursery, neutral to slightly acidic. (Necessary, water in his area is really horrid, 600-800 ppm TDS or more) Mine runs 250-350 most of the time. So I tested the hypothesis on a Catt that had been in Orchiata for about 5 years (definitely in need of repotting) and found that even though it was broken down and should have been leaching organic acids, when I tested what ran out of the pot, it was pH about 7.5 rather than 7.8 ..., those organic acids were no match for the calcium bicarbonate in the water.
At pH of 5.5 to 6.5, the absorption of the various minerals in fertilizer is optimized. That doesn't mean that above that nothing gets to the plant, just less. So when I used city water for fertilizing, I pushed the pH down into that range with vinegar. (Fertilizer high in phosphorus, such as 20-20-20, tends to lower pH, but again no match for the buffering from the water) For routine watering, everything that gets city water (most of the yard) gets what it gets. And seems to do no harm. For fertilizing I now use RO with MSU fertilizer, which then ends up in the right pH range because the pure water doesn't have any buffering capacity.
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