Please advise why https://diy.stackexchange.com/q/99930/54670 and https://diy.stackexchange.com/q/99934/54670 were unilaterally closed, and how they can be made on-topic again?
I ask because I had read the following that all seek recommendations too: What type of filters should I use for a 3 stage whole house water filter?, What kind of filter do I need for well water?.