(C) The payment shall be made in a form that is mutually acceptable to the parties or, in the absence of agreement between the parties, in the form of a cashier’s check or money order made out to the landlord.(4) If the tenant fails to make a payment in full compliance with the terms of paragraph (2), the landlord may, after 48 hours’ notice to the tenant by telephone, text message, or electronic mail, as stipulated by the tenant, file with the court a declaration under penalty of perjury containing all of the following:(A) A recitation of the facts constituting the failure.

Well, I pay water+trash and tenants pay electric, gas & telephone.

And the cellular provider that rents them space on their network is ethically to blame.    

Centers, ,Superior Court, ,Talk to Neighbors, ,Tax Liens, ,Tear Off Notices, ,Telephone Poles, ,Television TV Guide, ,Title Companies/Closing Agents, ,Trade Shows, ,TShirts and Hats, ,TV Guide Newspapers, ,Twitter, ,Uber Drivers, ,Uhaul Locations, ,Vehicles, ,Visiting Nurses, ,Walking Billboards, ,Web Links and Alliances, ,Web Page, ,Wedding Announcements, ,Weekly Hotels, ,Yellow Pages, ,Your Competitors, ,Your Contractors/Vendors, ,Your Existing Occupants, ,Your Voice Mail/Tell a Friend, etc

The TCPA regulates telephone solicitations, end of story...  

Read up on the TCPA (Telephone Consumer Protection Act), which imposes fines ranging from $500 to $1,500 PER TEXT MESSAGE. 

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Therefore I need a unique email address / telephone number set up in Zelle for each tenant.

Small company, a little bit of a pain to get set up, but it connects to a cellular network (not the tenant's wifi) and can either meter the water at point of use (each sink, shower, toilet, etc) or have a main meter if your plumbing is separated. 

It's usually handled with telephone calls.