Use a sharp knife or peeler, cut thin slices of the lemon skin (the zest) while leaving the white part of the rind behind.
Next cut the juicy flesh of the lemon away from that white part.
Add the water, lemon zest and pulp to your Instant Pot with the thyme and cook on manual/pressure cook for 5 minutes.
Let the pressure release naturally which can take from 15 to 20 minutes. This just allows the water to take on a stronger flavor.
If you are in a hurry wait until it's been on warm for 10 minutes, then carefully pulse the release value until the pressure is down. Since the pot is full of liquid there may be some hot water released as you do this, so be careful!
Strain, then store in the fridge for up to 4 days.