Cleaning a weed killer sprayer is necessary to prevent unintended harm to non-target plants and maintain equipment functionality. Chemical residues, especially from potent herbicides, can remain active within the tank, hoses, and nozzles, potentially damaging sensitive vegetation. Even trace amounts of chemical carryover can injure or kill plants, making a comprehensive cleaning protocol fundamental to responsible application. Regular cleaning also prevents residues from drying and hardening inside components, which can cause clogs, reduce spray accuracy, and lead to equipment deterioration.
Essential Preparation and Safety Gear
Securing the appropriate personal protective equipment (PPE) is paramount before cleaning, as you will be handling concentrated chemical residues. Wear chemical-resistant gloves that extend up the forearm, eye protection like safety goggles, and a long-sleeved shirt and long pants. A chemical-resistant apron or coverall provides an additional layer of defense against splashes and accidental skin contact, since many pesticides are readily absorbed through the skin.
Conduct the cleaning in a designated area situated away from immediate water sources, such as wells or storm drains, to prevent environmental contamination. This area must also be inaccessible to children, pets, and livestock. Begin by draining any remaining weed killer concentrate from the tank and lines. Spray this concentrate onto an area already targeted for treatment, as directed by the product label. This initial draining removes the bulk of the active chemical, which is the most concentrated and hazardous portion of the residue.
Step-by-Step Cleaning Protocol
The first step after draining the concentrate is a thorough pre-rinse of the entire system with clean water. Add water equal to about 10% of the tank’s total capacity. Circulate it briefly through the pump and hoses, then spray this rinsate through the nozzles for several minutes. This action flushes residue from the internal surfaces, ensuring the subsequent cleaning agent works more effectively against the remaining chemical film.
Next, select and mix a proper cleaning solution, which is typically specified on the herbicide label. If no specific cleaner is listed, a common choice is a solution of household ammonia (about one gallon of 3% ammonia per 100 gallons of water, or a 1% to 2% solution for smaller sprayers). Alternatively, use a non-ionic detergent or a specialized commercial tank cleaner to help dissolve both oil- and water-soluble herbicides.
Fill the tank approximately halfway with the cleaning solution and circulate it through the system for at least 15 minutes. The cleaning agent must contact all internal surfaces, including the agitator, pump, and the tops of the tank walls. Operate the pump to push the solution through the hoses and out of the nozzles for several minutes until the spray boom is fully filled.
For herbicides difficult to remove, such as growth regulator types, allow the cleaning solution to soak inside the tank for several hours or even overnight to fully neutralize the residue. After soaking, drain the solution and perform a second rinse with clean water, circulating and flushing it through the nozzles. It is also beneficial to scrub the inside of the tank walls with a soft brush during this stage, taking care to reach irregular surfaces or baffles.
Finally, disassemble all removable components, including the nozzles, strainers, and filters. Clean them separately in a bucket containing the same cleaning solution. These small parts are prone to collecting solid residues that can harden, so use a soft brush to dislodge any trapped material. After scrubbing, rinse these parts thoroughly with clean water. Perform a third and final clean water rinse of the entire sprayer system before storage.
Proper Disposal of Cleaning Solutions
The liquid waste generated during cleaning, known as rinsate, must be handled with care because it contains dilute concentrations of the herbicide. Never dump this rinsate down household drains, into storm sewers, or onto bare ground, as this poses a significant risk of water and soil contamination. The active ingredients, even diluted, can pollute groundwater and harm aquatic life.
The most environmentally sound disposal method is to spray the rinsate onto an area approved for treatment by the herbicide’s label instructions. This application must not exceed the maximum labeled rate for that specific area. If the rinsate cannot be applied to a labeled site, or if the cleaning agent used makes on-site application unsafe, the solution must be collected and treated as hazardous waste.
Contact the local waste management authority to determine the proper hazardous waste disposal facility or collection event in your area. These facilities are equipped to handle chemical substances safely and legally. Always store the collected rinsate in a clearly labeled, sealed container until it can be transported for proper disposal, ensuring it remains out of reach of people and animals.
Post-Cleaning Inspection and Storage
After cleaning is complete, carefully inspect the sprayer to ensure equipment longevity. Pay close attention to seals, O-rings, and gaskets, which are susceptible to chemical degradation and wear. Replace any components that show signs of brittleness or cracking, as these flexible parts maintain system pressure and prevent leaks during operation.
Once inspected, the sprayer must be dried completely to prevent corrosion of metal parts and the growth of mold or mildew within the tank. Running clean air through the hoses and nozzles helps remove remaining moisture from the internal lines. For components like O-rings, applying a small amount of vegetable oil can lubricate them, preventing them from drying out and cracking during periods of non-use.
Store the cleaned and dried sprayer in a secure, temperature-controlled environment protected from direct sunlight and freezing temperatures. Storing the sprayer indoors prevents plastic components from becoming brittle and protects metal parts from rust. Avoid storing the sprayer near fertilizers or other chemicals, as the dust and residues from these products can potentially corrode the equipment.