This is a simple rain gauge made from a plastic bottle. My father tought me how to do it.

We always use it for deciding if and when we should water our fruit trees. (keep in mind that on a hot summer day 4 or 5 mm of water a day evaporated from the ground, so if it rained 50 mm, you don't need to water your trees for about 10/12 days).

### Teacher Notes

Teachers! Did you use this instructable in your classroom?

Add a Teacher Note to share how you incorporated it into your lesson.

## Step 1: WHAT YOU NEED

MATERIALS:

_plastic bottle (conic or funnel shaped);

_strong tape;

_stick or cane.

TOOLS:

_cutter;

_permanent marker;

_scales or capacity measure for liquids;

_ruler.

## Step 2: PREPARE BOTTLE

remove labels with warm water, and cut away the bottom of the bottle with cutter.

## Step 3: MAKE MESUREMENT

_measure the open AREA of the bottle opening: r • r • 3.14 (measure the diameter, divided it in 2 and find the radius, then

do radius by radius by 3.14);

_now, knowing that if it rain 1l of water on 1 square meter it will correspond at 1 mm of water, we need to find out how many ml in your bottle that mm of rain fall on the ground will correspond (x). We need to use this formula:

1m^{2} bottle open area 1liter • bottle open area

-------- = --------------------- so: x= ----------------------------------

1 liter x 1m^{2}

this is an example using the measurement of my bottle, my bottle diameter was 8.6 cm ( than 4.3 cm of radius)

4.3cm•4.3cm•3.14=58cm^{2 }( 58cm^{2}=0.0058m^{2})

1m^{2} 0.0058m^{2} 1 liter • 0.0058 m^{2}

--------- = ------------------ so: x= --------------------------- so: x=5.8 ml

1 liter x 1m^{2}

another way to find your x is: calculate the volume of 1 mm of water on the area of open surface of your water bottle, and use that number to make the measurements on your bottle:

r•r•3.14•0.1cm^{2}=x (than transform it: 1cm^{2}=1ml)

## Step 4: MARK NOTCH ON BOTTLE

now you have found x.

_x is the corresponding measure on your bottle of 1 mm of rain fallen on the ground, so we need to use it to mark the measurement on the bottle.

_because the number you will find is so small I will multiplied it by 5 times (so it will correspond to 5 mm of rain fallen on the ground).

_pour in the bottle the milliliters of water you just measured (5x) and mark it with permanent marker (write 5 mm). you can use a capacity measure for liquids or a scales (1l of water weigh one kilo).

_keep adding milliliters and marking until you mark the whole bottle.

example of my bottle:

_my x were 5.8 ml

_5.8 ml•5= 29 ml (corresponding at 5 mm of rain fallen on the ground)

_I signed the 5, 10, 15, 20,30,40,50,70,100 and 150 mm of rain on my bottle.

## Step 5: MAKE THE PEDESTAL

place the stick on the bottle (like in the photo) and stick it with tape.

## Step 6: DONE

you 're done! place the pluviometer (rain gauge) in your garden (stick the cane in the dirt), far from trees or roofs.

empty after every rain: you just need to unscrew the cap of the bottle.

Runner Up in the

SciStarter Citizen Science Contest

Participated in the

Reuse Contest

## 9 Discussions

6 years ago on Introduction

Er... Why do you start your sentences with an underscore instead of a capital letter?

Reply 6 years ago on Introduction

Because each sentences with an underscore is a step (and so I wanted to mark them)... but I also forgot to use the capital letter.

6 years ago on Introduction

Love the math!!

Reply 6 years ago on Introduction

Thanks

6 years ago on Introduction

Why have I never made one of these... probably the math part .... Now there's no reason left :)

6 years ago on Introduction

Excellent use of math to solve a tricky problem.

6 years ago on Introduction

Very nicely done.

FYI you have a typo in step 3 ..

it should say 4.3cm•4.3cm•3.14=58cm2 not 4.6cm•4.6cm•3.14=58cm2

Reply 6 years ago on Introduction

thanks, i m going to change it immediately, thank for saying it!

Reply 6 years ago on Introduction

please if anyone see other mistake or incomprehensible things please let me know