You probably live in an agricultural area. Your nitrate levels are in the unsafe range. (anything over 10mg/l is considered unsafe). We have the same problem where we live so we use nothing but bottled water for drinking (and beer making). If possible you should get the spring water tested...
Another bag for you to consider is the one I use:
https://www.brewinabag.com/
I like it because it has straps sewn into the bag with loops at the top so it can be easily used with an overhead pulley or winch.
I get it at our local BevMo. In fact I just finished one!
https://www.bevmo.com/shop/beer_and_hard_seltzer/craft_brew/scottish_and_irish_ale/oskar_blues_old_chub_scottish_ale_6_pkc_12_oz/p/1564405684704491105#!/?department_id=897408
I haven't tried it but it seems like a forstner bit should work really well.
https://www.harborfreight.com/14-in-1-in-forstner-drill-bit-set-with-38-in-shanks-7-piece-62361.html
Here's what I have used for the past 20 some years. I have looked at some of the newer programs but since all my recipes are in PM and it still works just fine for me I haven't seen any compelling reason to change.
I've had their 3D mill for 20+ years. It does a great job and have had no problems. I've had a few questions over the the years and Don has always been very responsive. Highly recommended.
Sounds like you need to make your own. It's really pretty easy. I was able to do it and I'm a real klutz when it comes to anything like cooking. Here's a good thread on how to:
https://www.homebrewtalk.com/threads/20-lb-of-sugar-and-a-jar-of-yeast-nutrient.114837/