I do a lot of direct bookings that take security deposits, but with Airbnb, they are always tough.

First, request the current rent roll, which details each unit’s rental income, lease terms, and any security deposits.

Security Deposit: Follow Oregon’s rules—return deposits within 31 days with documented deductions.5.

Also, tomorrow I will be requesting a Deposit to Hold of $500 which will add to their legitimacy.

I have prospective tenants who signed a lease on 31st of October and paid security deposit same day.

Quote from @Kadia Lawrence: Deposits are refundable.

I don't withhold security deposit returns for BS things.  

Also forces the seller to deal with the deposit reconciliation. 

How should the security deposit be managed in this transition?

I think this would make sense in the long run for the rental property as it will extend the life of everything it touches like the Sink, faucets, showers, water heater, dishwasher, and Clothes washer while also providing clean drinking water in addition to the reverse osmosis drinking water system I already have installed.The main problem with this hardness level is that we get a major deposit buildup on all of these items, which will eventually clog up the faucets for tenants and lead to rusty shower enclosures that take forever to clean.In addition to this, it looks like we could likely have the salt added every couple of months by the property managers in addition to that it would allow for a quick inspection from them, and then also we would instead bill the cost of the service onto the ledger for the tenants.For reference, it does not look like the landlords in the area have water softeners.Thank you everyone for your input ahead of time.