There are two ways to get a Letter of Medical Necessity for a water filter: the built-in checkout route, or asking your own provider. Here is how each works, what providers look for before signing, and how to prepare so you qualify.
Two routes
Get your letter through a checkout that issues it (fast, no appointment) or from your own provider. Either way, a licensed provider must connect your filter to a health condition and sign before you buy.
The simplest path is buying from a retailer that issues the letter at purchase. You answer a short health survey, a licensed provider reviews it, and the Letter of Medical Necessity is issued — often within hours, with no appointment. This is how SpringWell's TrueMed checkout works; see the full walkthrough.
If you prefer, your treating physician can write the letter. Bring the request to a regular visit, explain the water-quality concern and any test results, and ask them to document the medical necessity. This works well if you already have a relevant diagnosis on file. Use our template and example to show your provider exactly what the letter should contain.
A provider is making a clinical judgment, so they want to see a genuine link between your water and a health condition. Strong supporting elements include:
General consumer-health context from the CDC can help you frame the conversation, but the determination is the provider's.
The letter must be dated on or before your purchase — retroactive letters are not accepted — and it is generally valid up to 12 months, which matters for replacement cartridges. After it lapses, renew if you continue reimbursing replacements.
SpringWell's eligible systems issue the Letter of Medical Necessity through TrueMed during checkout — the fastest route for most buyers.
Shop eligible systems →While only a provider can decide, these situations frequently support a medical-necessity case:
Keep it concrete: describe the contaminant concern, share any test results, name who in the household is at risk, and ask whether they can document a water filtration system as medically necessary to treat or prevent the condition. Bringing the template makes it a two-minute request rather than an open-ended conversation.
Some clinicians have not written one for a water filter before. That is fine — the concept is standard for durable medical equipment. Show them the template, explain that your FSA/HSA administrator accepts a Letter of Medical Necessity, and offer your test results as support. If it is easier, the checkout route handles the provider step for you.
Through a partner checkout, the letter is typically provided at no separate cost. Through your own provider, a brief visit may carry a normal copay — though if you are seeing them anyway, adding the request costs nothing extra. Either way, the letter unlocks tax savings that usually dwarf any small cost to obtain it.
Either through a checkout that issues it after a short health survey (fastest), or by asking your own treating provider to write one based on your condition and water-quality concern.
A genuine link between your water and a health condition: a documented or preventable condition, evidence about your water (a test or utility report), and a filter that actually addresses that contaminant.
Not strictly, but a test result or utility report is the most persuasive supporting document and helps the provider make a specific recommendation.
Generally up to 12 months for the same product category. Renew it if you keep reimbursing replacement filters after it lapses.
