Gerbils need access to fresh clean water at all times. Water bowls will not work as gerbils will kick their bedding into the water. Water bottles allow for a gerbil to gently sip and is less likely to be dumped or soak the bedding as bowls do.
A 4oz Bottle is big enough as this is changed daily and gerbils drink very little. If you purchase a plastic bottle you will need to monitor for chewing. Some bottles come with a spring ball for the sipper these are great for gerbils who are constantly kicking their bedding against bottles.
I have found that a 15 inch tall tank works great with 4oz bottles and 6-8 inches of bedding. I also place something for them to stand on to reach their bottle for when they kick bedding away from it. To hang a water bottle from a glass tank use industrial strength velcro.
You should really scatter feed to encourage natural behavior, however a food dish is a great storage type feeding. I like to scatter feed as well as providing a small dish with food. One adult gerbil should eat one tablespoon per day. If you leave a bit more don’t worry gerbils won’t over eat.
Gerbils love to take sand baths. The sand helps keep their coat soft and oil free. When selecting a sand make sure it is Chinchilla Sand as powder and dust baths can get into their eyes and respiratory systems. A small aquarium bowl is great for keeping the sand contained. Leave this in their tank and they will also use it as a bathroom which helps keep their tank fresh. If you leave it in their tank make sure you sift it daily.
The best exercise for gerbils is to let them run in a playpen or in a dry bathtub! You can even sit inside with them and let them climb on you making taming much more easier!
Wire and wire mesh wheels (photos 1 & 2) are not safe for gerbils as their tails, legs and toes can get trapped between the wires resulting in injury. Wire wheels are also extremely noisy. The Silent spinner (3rd photo) is a solid wheel made of hard plastic, you will need to make sure your gerbil is not chewing on the plastic. Keep it out of the bedding and most gerbils will not chew it. The silent spinner can be hung from the glass using command hooks. The last photo is a wheel made of wood and is safe to chew.
Some gerbils show no interest in wheels while others enjoy them time to time. I have one who is obsessed with her wheel and limit her by taking it out at night. If your gerbils show no interest you can simply take it out to allow for more toys. It is not critical as it is with hamsters for a gerbil to have a wheel.
Hamster balls are a bit of a debate. This product is made of plastic. Not only can gerbils chew it they will also use it as a bathroom and roll around in their own urine and feces. Yuck! They are poorly ventilated and when a gerbil does relieve themselves in it they are trapped with the ammonia. These balls do have slits on both side that over lap to keep animals from getting limbs trapped. However, being gerbils they can chew it creating a big enough hole for toes to get trapped.