diff --git a/water_sensor/water_sensor.ino b/water_sensor/water_sensor.ino
new file mode 100644
index 0000000..447433b
--- /dev/null
+++ b/water_sensor/water_sensor.ino
@@ -0,0 +1,98 @@
+#include <RCSwitch.h>
+#include <avr/sleep.h>
+#include <avr/power.h>
+#include <avr/wdt.h>
+
+// Utility macros
+#define adc_disable() (ADCSRA &= ~_BV(ADEN)) // disable ADC (before power-off)
+#define adc_enable()  (ADCSRA |= _BV(ADEN)) // re-enable ADC
+#define enable_pin_interrupts()  (GIMSK |= _BV(PCIE))  // Enable Pin Change Interrupts
+
+// Pins
+#define SWITCH 0
+#define SENDER 2
+#define CONTROLLER 4
+
+RCSwitch mySwitch = RCSwitch();
+char* CIRCUIT_OPEN  =  "00000000000000000000000001000011";
+char* CIRCUIT_CLOSED = "00000000000000000000000001100011";
+
+int counter = 0;
+
+void setup() {
+    
+  pinMode(SWITCH, INPUT_PULLUP);
+  pinMode(CONTROLLER, OUTPUT);
+  digitalWrite(CONTROLLER, HIGH);
+
+  mySwitch.enableTransmit(SENDER);
+  mySwitch.setProtocol(2);
+
+  sendWindowState();
+
+  set_sleep_mode(SLEEP_MODE_PWR_DOWN);
+  enable_pin_interrupts();
+  enableWdt();
+
+}
+
+void loop() {
+  sleep();
+}
+
+bool readState() {
+  digitalWrite(CONTROLLER, LOW);
+  bool state = digitalRead(SWITCH);
+  digitalWrite(CONTROLLER, HIGH);
+  return state;
+}
+
+void sendWindowState() {
+  if (readState()) {
+    mySwitch.send(CIRCUIT_OPEN);
+  } else {
+    mySwitch.send(CIRCUIT_CLOSED);
+  }
+}
+
+void sleep() {
+  PCMSK |= _BV(PCINT0);                   // Use PB0 as interrupt pin
+  adc_disable();
+  
+  sleep_enable();                         // Sets the Sleep Enable bit in the MCUCR Register (SE BIT)
+  sei();                                  // Enable interrupts
+
+  sleep_cpu();                            // sleep
+  
+  cli();                                  // Disable interrupts
+  PCMSK &= ~_BV(PCINT0);                  // Turn off PB0 as interrupt pin
+  sleep_disable();                        // Clear SE bit
+  adc_enable();
+  
+  sei();                                  // Enable interrupts
+}
+
+ISR(PCINT0_vect) {
+  sendWindowState();
+  delay(5000);
+  sendWindowState();
+}
+
+ISR(WDT_vect) {
+  counter++;
+  if (counter % 220 == 0) {
+    counter = 0;
+    sendWindowState();
+    delay(10000);
+    sendWindowState();
+  }
+}
+
+//enable the wdt for 8sec interrupt
+void enableWdt()
+{
+    MCUSR = 0x00;
+    WDTCR |= _BV(WDCE) | _BV(WDE);
+    WDTCR = _BV(WDIE) | _BV(WDP3) | _BV(WDP0);    //8192ms
+}
+