if you order through them and order a few at once its the same shipping theres a new 1 not on the site yet that's a charcoal based deep cleanse that's amazing! so you can just request 1 of the others you ordered be replaced with that.. the vinager rinse might work.. but its highly likely that all you n would need is a distilled or filtered rinse
some with very hard water just get a in shower head filter or filter on their entire water system
some off the grid friends made a solar water distiller
just the shampoo change with or without the charcoal deep cleanse would most likely be enough too
bronners should come out with just better water...but
you mentioned being in the barn being dirty etc dirt stuck in the gunk might not.. all the dreadlockshampoo shampoos super clean incredibly well
but the charcoal cleans your dreads so well that drinking the rinse water by sucking it right out of your dreads tastes so much better then the tap water that you could bottle it and sell it.
so depending on how bad the problem is it still should be very easy to fix
a couple gallons of spring water or distilled water would be a good start
if you had a few years worth of buildup id definitely grab a charcoal
inline filters aren't cheap, but in the long term very hard water can destroy your plumbing and the filters are ultimately cheaper long term then plumbing bills and repairs
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My new book Ban The Taboo Vol 1