Agree: surprisingly you will get build up even with freshwater (though not as quickly). Here you can see the build up of Urinary Struvite in my Vacuflush S series pump
after light use for 10+ yrs. Most folk's urine is alkaline and, even using freshwater exclusively, this stuff is rock hard and took several hours/batches of Muriatic acid to dissolve. Naturally my hoses, holding tank
, tank monitor
sensors were all encased also. Now I regularly add some mild acid weekly per Peggy's recommendation.