Competition preparation is mostly about removing uncertainty.
You want the coffee to perform.
You don't want your water to change unexpectedly from one practice session to another.
That makes water preparation an important part of competition workflow.
Start with a controlled base
Use a consistent low-mineral water as your starting point.
RO or distilled water can provide a controlled base when properly prepared for drinking use.
The advantage is repeatability.
If the starting water changes every time, the mineral profile you build on top of it changes too.
Prepare the mineral profile in advance
Once you've chosen a starting profile, prepare enough water for the entire practice session.
This prevents small differences between cups.
Label the container.
Record the date.
Record the composition.
Record the measured TDS if you use it as a checkpoint.
Taste the water
Before brewing coffee, taste the water itself.
Check for:
saltiness
metallic notes
chemical notes
unexpected bitterness
or other obvious defects.
If the water tastes wrong, don't expect the coffee to hide it.
Check TDS consistently
If you're using TDS as part of your quality control, measure consistently.
Use the same meter.
Use the same measurement procedure.
Allow the water to reach a consistent measurement temperature if your meter does not compensate automatically.
Remember that TDS is an estimate based on conductivity.
It is a consistency check, not a full mineral analysis.
Record the actual composition
If you're competing seriously, keep more information than TDS.
Record:
calcium
magnesium
alkalinity
and other relevant ions.
This allows you to reproduce a water profile rather than simply reproduce a meter reading.
Separate brew water and bypass water
If your AeroPress recipe uses bypass, decide whether the bypass water is the same water as the brewing water.
If it isn't, record both.
The final beverage is a combination of the two.
Prepare for the competition environment
Competition conditions may differ from your home environment.
The available water, equipment and preparation constraints can affect what is practical.
Always check the current official competition rules before finalising your preparation.
Rules can change between championships.
Practice the complete system
Don't practice only the water.
Practice:
coffee
grinder
water
temperature
AeroPress
filter
agitation
press
bypass
and serving.
The water is one part of the system.
Build a repeatability test
Before competition day, brew the same recipe several times.
If the sensory result is inconsistent, investigate.
Is the grind changing?
Is the water changing?
Is your pouring changing?
Is the temperature changing?
Repeatability is more useful than one spectacular cup.
Don't chase a number
A competition water doesn't need to hit a magical TDS.
A published championship recipe may use one number.
Another successful competitor may use another.
The important question is whether your chosen water works with your coffee and recipe.
The Water Artist
Competition water is controlled brewing water.
Not magic water.
Build it consistently.
Measure it.
Taste it.
Then let the coffee do the talking.
Water is the canvas.
You're the artist.