ph around grey water

I am weeding and replanting the greywater area and I happend to measure the ph of the soil (once only), but I will promise to do more...
I never did it and expected that the soil was alkaline because of all that soap but it was around six. Out soil around is a terrible patchwork so nothing to compare with.
What is your experience? Didi you measure? Could you do some tests please?
If the soil does not get alkaline around the greywater pond reedbed then the plants which can be planted are of a greater range. BTW I had this greywater area since some years.

From what I've read the overall PH of grey water tends to be close to 7.

The PH of soil is set mostly by the soil, not the water, and changing the PH of soil (except temporarily) is very difficult to do.  Have you measure the soil PH in other areas that don't get grey water?

That is actually positive if the soil is not affected by the grey water. The soil around there should be alkaline because it is the soil I didn't do anything about it (improve) but I didn't measure. As far as I know the story goes don't use grey water at the same spot because it does something bad to your soil...

My grey water was pH 6.5 the one time I had it tested.

What kind of soap are you using in your greywater? In my laundry to landscape system, I use greywater approved detergents only. My preference is Oasis brand but I have to drive a ways to get it. otherwise Ecos from Costco, but it looks like your in Australia, so I'm not sure what's available to you. My parents used castile soap in their laundry to landscape system without any long term issues.