Water Intake Band


September 26, 2021

An inexpensive, universal water consumption tracker that lets people use their own water bottles to work towards appropriate hydration levels. Easy to manufacture and customize, with great potential for direct sales to businesses in the health industry.

Invention idea #03133.1 pulled from my notebooks to share.

Build it for fun & profit.

Explore the interactive blueprint.

Click/Touch & drag to pan, Scroll wheel/pinch to zoom.

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Overview of the concept:

Additional Thoughts:

I originally called it the “Water Intake Tracker”, but settled on “Band” since it was more descriptive, less obscure, doesn’t get aliased with other personal water management devices, and easier for people to recognize what it is by name.

A spin on this idea that I didn’t mention previously is to sell only the marker to wristband manufacturers. This way they can print their own bands and you wholesale them a cases of markers to use with it. They can offer pre-printed bands with your markers. This saves them the trouble of manufacturing the marker and lets them focus on what they do best. 

I’d also look at promotional product companies. These companies buy cheap widgets and slap company names on them to be distributed to customers (EG: conventions). The Water Intake Band would be a nice fit. They usually offer custom wristbands, so all they have to do is buy your markers, print bands with the indicators/company artwork, and offer them in their catalog. I'd send them a template for the indicators on the band to make it easier for them to layout. The nice thing about this sales channel is usually they sell in the 1-10k mark to a larger company so your volumes would be "tasty" once you get going. Plus, they do all the footwork direct marketing to companies.

Marker Proof of Concept:

I built a quick proof of concept (POC) to play with the idea. This should be a good starting point for a final marker design.


  • The STL for the POC1 will need refinement for final since the sharp edges that contact the band will prematurely wear out the band. [Ref1]
  • You can tighten the clearance a bit on the marker to save on size and material costs (I left 1mm slip fit for the band).
  • Front surface should be curved as drawn in blueprint for safe, tactile use.
  • If you download OpenSCAD, you can open the attached SCAD file and play with the parameters/code to change the design as desired.
  • When printing, lay the model on it's side for best durability so that band stress is perpendicular to print layers.
  • This design is for 3D printing. If you want to mold inject you’ll need to use a solid modeling program like Fusion 360.

Starting Point for Proto1:

I tested the POC1 with a stock 8” silicone band. It was too tight for large 16-32oz bottles but works nicely on smaller 14oz bottles and even better on pre-packaged bottles of water. I used these as models to estimate a reasonable starting point for a PROTO1 band circumference that should fit most water bottles, and provide decent grip/slip of the marker with pressure.


(1) Get average diameter across sample sizes.

Measured Diameters of Water Bottle Samples:

  • 16oz Bike Bottle: 2.9” (73.66 mm)
  • 32oz Bottle: 3.4" (86.36 mm)
  • 14oz Bottle: 2.7" (68.58 mm)

Average Diameter from Sample:

(2.9+3.4+2.7)/3 = 3” (76.2 mm)

(2) Get slip fit offset from 8" band test cases.

Measured Diameters of Pre-packaged Water Bottle Samples:

  • Dasani Bottle: 2.6” (66.04 mm)
  • Crystal Geyser Bottle: 2.5” (63.5 mm)

Average Diameter from Sample:

  • (2.6+2.5)/2 = 2.55" (64.77 mm)

Circumference Slip Fit Offset from Sample:

pi*(64.77) - Band Circumference = 8.011" - 8" = 0.011" (0.254 mm)  = Slip

(3) Calculate final band circumference for PROTO1

Start point: 3" (76.2 mm) diameter -> 9.42” (239.27 mm) => 9.42+0.011 = 9.43” (239.52)


As you can see, the slip offset is negligible, so a good starting point is really just the average of the bottle diameters you want to fit. In my case I'll want to order a custom band about 9.42 inches in circumference.

Notes on Band:

As I mentioned in the audio, you can get custom band circumferences made with no cost in tooling. I called one such supplier in the US and talked at length about custom sizes. Short story is it would only bump the cost per unit by a little, there is a 50x minimum, and for an accurate quote you need to submit a custom request to them for numbers. They also offer 3/4” and 1” width bands.

I threw together an SVG POC for a 0.5 x 9.5” band so you can play with layout. Attached below.

Using this concept, it's obvious you'll run out of space for smaller bottles since they would require more refills/indicators to get the proper hydration levels. To avoid this, a better approach may be to buy the 3/4" or 1.0" bands and put an indicator along the top edge. Something like this:

This allows a large number of indicators on the edge and plenty of room for logos and copy. I probably wouldn't go nuts with 20 indicators though. 5-10 seems reasonable for most body weights and bottles in my opinion. However, if you direct market this to health/fitness companies you can let them specify how many indicators they want. Perhaps if they only want 5x, then they can do the 1/2" bands. If they want 10x then bump them to the 3/4" band. So on.

Originally, I visualized putting the formula on the band artwork so people can calculate hydration levels. It still may be an interesting idea for a generic band you sell on Amazon directly to consumers; however, it may be better to include a small business card sized chart in the package to let them “look up” their weight/bottle/hydration level and save the band space for artwork.



  • "wib-markerV1.stl" is licensed under CC BY-SA 4.0.
  • "wib-marker.scad" is licensed under GPLv3.
  • "wib-band.svg" is licensed under CC BY 4.0.
  • "wib-wideband.svg" is licensed under CC BY 4.0.

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